Saving someone you don't like or who isn't someone whose well-being you're personally invested in is more admirable because it's selfless. It's charity, which is what is meant by Biblical 'love' (the "love your enemy/neighbour" sentiment isn't about wanting them over for Sunday brunch, it's about treating them with respect, fairness, and seeing in them the same worth as any other person no matter your personal feelings). I would call that pretty objectively true.

So you could say Severus has cornered the market on Biblical love or 'charity' in his selfless protection of people who do nothing to deserve it from him.