" Also presumably, there would be plenty of "humans" patrolling this category. Truly non compliant images would still get tagged."
Thats the problem. I would presume the opposite, in fact, and thats why we've got bots to begin with.
In order to argue that the bot is doing something wrong (the bot itself, not Betacommand) you need to point out where it is not obeying policy. If you look at WP:AN/Betacommand, you'll note that there is no (and has never been a) consensus that BCBot stop operating. The fact is that it is obeying policy, so your next step is to *change the policy.* This can be done, by consensus, and is by far a better approach than attacking a bot that is enforcing the letter of current policy.
Betacommand, on the other hand, may not have the communication style best suited to the bot operator. I won't ding him for getting pissed off, I would, but someone a little more communicative and verbally dexterous might have an easier job of it.
Nathan