1) if pg doesn't have some well thought out and articulated perspective on moral questions, that's OK - he's not a priest
2) Saying it's alarming is basically pushing him and people like him into taking a (probably artificial) position for the sake of taking one.
3) Just because one is powerful doesn't mean one has to be a role model in all areas of life. This is unnecessary pressure on an individual who hasn't asked for it - he's basically a sort of VC, he isn't running for president - and I don't see anything good coming out of it.
I chose a utilitarian belief system as an example because it felt like the most non-controversial one to make a point. Incidentally, I don't subscribe to it.
Agreed about humanities, but I don't really see the connection to your OP.
Here's a highly related essay by pg, by the way: http://www.paulgraham.com/identity.html