Maybe you even make it [wanting to direct your efforts elsewhere] look more 'rational' by name-dropping expected utility.

This is an interesting point. It has often been my experience that the proposition "helping friends work out mental bugs is a good use of time in expectation" feels true in the abstract more often than it feels true in the sum of all particular cases.

I'm currently inclined to say that helping friends work out mental bugs actually is worth it in general, though I am currently in abstract-thinking mode as I'm saying this. ;)