I am not a Roman Catholic and not a huge fan of much Roman Catholic theology. But I had long thought that, when it came to social teaching and hard-headed moral thinking, the Roman Catholic Church was light years ahead of most Protestants in both sophistication and precision.
It's hard to know what to make of Trueman's terse statement.
i) Many "social justice" positions taken by the current Magisterium are interchangeable with the platform of the Democrat Party. Perhaps Trueman's position is affected by the fact that he's English. In general, conservative Americans are quite hostile to the welfare state, but perhaps that's something which differentiates them from Trueman. I'm not suggesting that the English automatically support the welfare state. Maggie Thatcher was a notable critic, but she was controversial for that very reason. Indeed, she may be more popular among American conservatives than many Britons. Peter Hitchens disdains her, although Roger Scruton admires her.
ii) I wonder how conversant Trueman is regarding evangelical ethicists. Perhaps this reflects Trueman's disdain for evangelicalism–in contrast to "confessional Calvinism". There are sophisticated expositions of personal and social ethics, viz. John Jefferson Davis, Evangelical Ethics; John and Paul Feinberg, Ethics for A Brave New World; John Frame, The Doctrine of the Christian Life; John Frame, Medical Ethics: Principles, Persons, and Problems.
iii) It's true that Catholic ethicists can argue with great precision and sophistication, but to what end? Their job is not to ascertain right and wrong, but to defend whatever the Magisterium deems to be right and wrong. They begin with the diktats of Rome, then cast about for supporting arguments to retroactively rationalize a foregone conclusion. And it can take tremendous ingenuity to defend Catholic moral theology. Consider the hairsplitting distinctions that are required to attack artificial contraception while defending natural family planning. Or to attack divorce while defending annulment, or to attack lying while defending mental reservations. Perhaps, though, Trueman is using "social teaching" in a narrow sense, rather than Catholic moral theology in general. Even so, Catholic social teaching reflects misplaced precision and sophistication. Not sophisticated analysis to arrive at the truth, but sophisticated special pleading to justify whatever Rome says. Not precision to be conceptually accurate, but precision to draw ad hoc distinctions.