Pretty much, yeah. He was brave, I don't think the OP is trying to say otherwise. But he WAS jealous, vengeful, even sadistic. If Voldy had decided that the child in question was Neville Longbottom, Snape would have merrily continued on his way not caring that he condemned a family including an innocent infant boy to death (and he passed on the secret knowing this, as well). As the OP says, "oh hey, I'm totally cool with the murder of innocent kids, but don't touch the hottie"