His answers seem quite concrete to me. He even links further reading after answering questions directly. I don't really see any platitudes or non-answers at all. Maybe it's predictable? But it seems his answers are genuine, to-the-point, and even provides the reader with further reading. Not sure what more you could ask for really.

Edit: I mean, look at this answer: https://www.reddit.com/r/IAmA/comments/aunv58/im_bill_gates_...

Seems solidly real to me.