There may be fewer evangelical intellectuals but that's not the only reason Cowen doesn't meet them
I am open to this argument, but I think you are underestimating the gap in phds by religious tradition. As someone who has some inner knowledge of at least one prominent Conservative Christian higher education institution, and one smaller, less prominent one, both have serious issues recruiting Evangelical talent, particularly in the social sciences like economics, political science, and sociology.
Obviously Protestantism is a broad tent, but at least amongst those whom we would consider Evangelicals, their corner of the tent is very sparse with folks who are trying to get PhDs, at least in the humanities and social sciences.
I hesitate to write this because it may come across as being disagreeable when I'm only attempting to focus upon differences of moral formation, historically, between Protestants and Roman Catholics.
I'm reading a good book right now - The Roots of Reformed Moral Theology by Bruce Baugus.
It helpfully provides that history, both in the OT, NT, and the Church as to how moral theology developed alongside the phlosophy of ethics in general. The two overlap but are not coextensive. Some historians, for instance, have attempted to argue that the Jews borrowed from Greek phlosophy to develop their ideas about how to act in society while others have attempted to show that the Greeks copied the OT Scriptures.
Regardless of where you fall down, the Church did not historcially try to develop a phlsophy of ethics from generally agreed upon pricniples but from what they believed was revealed by God. There was futher development in the Medieval Church that more or less developed a tradition that included asceticism and other moral practices to the poitn at which the Reformation came in and the Roman Church diverged from the Reformed Churches in terms of moral conduct.
The reason why the Roman Church developed a much more extensive system of causistry around moral practice owes, in no small measure, to their Sacrament of Penance and the "rules" around what is or isn't a venial or a mortal sin. This matters because the Church needs to know what to tell a person to "do" with respect to penance.
Add to this a difference, historcailly, on the nature of mankind and whther concupiscence is sin or it is a tendency toward sin. The Roman Church has a much higher view on the good the man is capable of doing without grace.
I think that if you look, historically at Protestant Churces that emerged drom their Confessional moorings, you will have seen communities that were engaged in trying to follow an ethical sytesm of living that was rooted in what they believed the Word of God told them. In the Roman Church, the system was a set of clear, even philsophical outworkings, as to what the Church had worked out. The latter system lends itself much more to being a holistic system while the Portestant system has always tied to provide principles of "general equity" as to how a person should live their lives. There is also a very clear, herarchical system that a Roman Catholic can turn to in order to say: this is what the Church teaches.
I don't think there was ever a time where the "Preotestan establishment" had a sort of Erastican system of how the people and the state should operate. While the State in Eurpoean nations was the defender and promoter of the State religion then it feflected the general convictions of that Church. In America, while the people were mostly Church going and believed the things that the Sciptures taught then a gernal sense of Protestant etihics prevaled.
I don't know if I'm making any sense out of this, but I am skeptical of attemtps to create a "Protestant consensus" that tries to provide some sort of institutional unity and "respecatblity" for Biblical ethics. Thsoe of us who are successful in business and government (I've done both) have few illusions that we'll see a return to the time whern there was a Protestant consensus. In fact, those trying to "rebuild" this may larn a lot from the Evangelical and Catholics Together (ECT) movement of the mid to late 90's as Chuck Colson and others were tyring to fill the void created by the retreat of Protestant Liberals from the moral center of America's moral formation. That only proved that many Protestants are so desparate for "moral formaiton" that they will compomise the defintion of the Gospel itself in order to create a respectable power bloc with Catholics.
I'll close with an anectdote. I was listening to a popular podcast that talks to tehcnical, political, and ecnonomic trends. One of the hosts is a powerful Lesbian journalist while the other is an entrepeneou. They were both appalled by the new Speaker of the Hourse, calling him a wahacko and a "Christan nationalist" because he claims to get his ethical ideas fromt he Scriptures. I don't see the current Speaker as a paragon of Christian theology, but it's nigh impossible for a ture, historical Protestant ethic to take hold if Protestants are forced to deny that their ethcial formation is inextricably connected to what the Scirptures teach either directly or by good and necessary consequence.
For a non-religious person, Cowen is remarkably fair to religious thinkers and ideas. All of his "Conversations with Tyler" are interesting, but the ones with David Bentley Hart, Cynthia Haven, Dana Gioia and Ross Douthat (3 RC and 1 EO) give an idea of how he handles religion.
I think part of this relates to what you've written already about the decline of the mainline. I think it also has to do with the decline of public school education. Catholics have their own schools from K-PhD. Protestants had their own schools too, Harvard, Yale, publicly funded schools that said the Lord's Prayer every morning, etc... Now the public schools are secular. The Catholic schools are secularizing, too, but at a slower rate. There are outlier groups like the Christian Reformed Church that has its own Christian Day Schools and some universities too. But, at least when I was at Calvin University there was a pipeline moving back and forth between Calvin and Notre Dame.
The homeschooling movement among some evangelicals is too small to make the kind of difference that a large Christian School or network of Christian schools can do.
A lot of this does turn on the anti-intellectual bent of the fundamentalist reaction to theological liberalism. Couple that with an a-historical approach to Christianity that seems blissfully ignorant regarding recent Christian events in the past 2000 years, and the Protestant Christian Scholar will struggle to find peers that aren't secular, aren't theologically liberal, and aren't Roman Catholic.