Oh, I wouldn't call Snape a non-hateful person. The guy had so much bitterness bottled up in him that that would be going a bit far, don't you think?

But he didn't hate Lupin as much as he hated what he stood for, and who with. Lupin himself was never a controversial character, the only reasons people had for disliking him was the fact he was a werewolf, or because of his closeness with James and Sirius (like Snape).