Or he could hate them, and have sworn he'd never be like James and get someone killed just because he hated them. Sure, that doesn't line up well with being a death eater, but I could imagine him having said that's something I'd never do shortly after his life had been endangered. And the one thing Snape has consistently been is, in DnD terms, lawful. He is massively lawful and that's part of why he hates James and Harry - they're both chaotic. My favorite description of Snape remains "Lawful Unpleasant".