Horns are only found on herbivores, and are for defense or wrestling other bucks in the breeding season. While they are fun to add to make a creature look scary (done it a few times myself) basically: horns = not going to eat you. So now I'm curious, did you include horns on your Beast due to Disney influence, or the symbolism?
Though, “original” BATB beast is noted to be scaly, have a trunk, horns etc, so like… it’s sort of an anything-goes situation. While you’re correct on the non-predatory angle, many animals that we know as horned or antlered herbivores, including deer, will consume bones and carrion if given the opportunity. Anyway, I’ve said before I’m not a brilliant designer, if he loses the horns he’s just a scrawny lion-dog. He needs the cool points wherever he can get ‘em!
(That and I thought he could get down low in a running herd and just gore the living heck out of deer’s stomachs. Hard to run when your entrails are all spilling out…)