I think you're playing games with the definition of 'brave' there. "Well, I've done X, and I don't think I was brave, so if Snape does Y which is sort of similar to X, he can't possibly be brave." I wish that there'd been a bit more focus on Snape while he was alive in DH, and some interaction with Harry, but Rowling does many things that seem odd to me, storywise.

I agree with the comment that that Harry, in Rowling's view, has nothing he needs to redeem himself for (he condemns Dumbledore's stumble with Grindelwald, saying youth is no excuse, while failing to make any connection to his own youthful hubris which contributed to Sirius's death.)