Well, you've also, you've gotta look at intent here. From both a societal and theological perspective, this makes perfect sense.
Animals have absolutely no means nor the intelligence to give consent, and even if they did, there are anatomical incompatibilities that would potentially cause one of the individuals irreparable harm. These wouldn't be treatable, as their veterinary medicine was quite literally millennia behind what we have now, and the animal would likely subsequently suffer for the rest of its life. In addition, they didn't particularly know how genetics worked back then, and had no idea what would happen anyway.
The fear of some sort of hybrid monster, coupled with the unethical lack of consent, coupled with the irreparable damage that the animal was caused, coupled with the lack of veterinary medicine, means that, yeah, killing the person who did that and mercy killing the animal so it doesn't suffer are the logical things to do.
Now take the classic "furry" anthropomorphic animals. They're more human than they are animal; their anatomy and intelligence are more akin to people. They can fit into society just like a person, and would have the same set of rules applied to them as a human, thereby eliminating the theological and societal problems that that verse is attempting to cover for. And that's if sexual themes are even present, which, in many cases, they're not. In many cases, they are, sure, but that's not a criterion.