Steal in that context is a powerful word as it blatantly suggests he already accused all customers of being a thief of some sort. Not only that, he is trying to guilt people into buying his product with the follow up sentence, "why would you steal from a vet".
I think you should re-read the post with the mindset that he is, after all, a comedian. Sure, this is an issue we all care about here, but there's no need to be overly serious about the tone of Jim's post. He's trying to come off as funny.
He is doing it wrong.