Many animal welfare laws exempt rats and mice.

Also, Animal Hoarding is about more than just numbers- its about the conditions the animals are kept in. Are they belly deep in crap? are they half-hairless from mite infestation? are there dead animals decomposing next to the food dish? Is there even food or water available?

Presumably, you want your snakes to be healthy, so whether you actually care about the rats/mice for their own sakes or not, you are probably at least keeping the compartments clean, removing sick/dead animals, regularly feeding them and proving clean water at all times, etc.