If education is signaling, does moral signaling become a viable major?

In a recent post, I encountered an interesting empirical fact about the college wage premium accruing to low-ability college grads over the period 1979-1994. Looking at a 2003 article by Tobias,  I wrote: "There is a lot of temporal volatility for the class of low-ability individuals. In fact, for low-ability individuals there is not even a consistent wage premium enjoyed by the college-educated until 1990."

I have begun to wonder if this pattern has anything to do with the non-linear relationship between GPA and PC. If the low-ability college entrants feel they are much less certain to enjoy a wage premium over the "townie losers" they left behind, what better strategy than to invest their college-specific word games with extreme moral significance?  That way, even the dumbest college grad can be confident that they will remain distinguished from the more able among the non-college-grads.

[Hat tip to a few high-quality comments on this blog recently, I don't recall exactly but I think someone may have made a point similar to this; the seed of this post might have been planted there, thank you.]

Although this last point is only conjecture, it is curious that right when the wage premium for low-ability college grads arrives is right when the first wave of campus political correctness kicks off — the early 1990s. Especially if you buy Caplan's signaling theory of education, it's not at all implausible that for low-ability college grads their wage-premium is secured primarily through a specialization in moral signaling