The stronger argument is that animals aren't as aware as humans which actions will have consequences. Animals do have customs about what's okay and what's not, but they often don't align with human society's laws.
It's "ignorance of the law is no excuse" taken to an extreme.
For another argument, consider that if you went into the woods and were mauled by a bear, nobody who found your body would feel the need to confront the bear and hold it responsible. The bear would not need to be convicted in order to be acted against.
That is true, but also not related to what your GP was talking about IMHO.
I understood their comment as coming from a perspective of either "you should fear what you can't understand/explain - and you can't really understand animals" or "it's their nature to be violent, it doesn't matter whether you understand them", either of which I think is flawed.
You made a much better point.
I just have a habit of picking at reasoning even if I agree with the conclusion. Sometimes you end up with a more concise and to the point argument at the end of that, and in this case it came from you!