The sentience angle is just dogmatic/philosophical and lacks any good evidence.
A service dog can be brought into a theater just fine, as it is sufficiently intelligent to be trained to behave appropriately.
There's nothing that specifically prevents animals from entering a movie theater, I'ma say they mostly just generally lack 1) any intellectual desire/intent to watch a movie, 2) appropriate social behavior to cohabit a space with humans, 3) money to pay their ticket.
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I would agree that current ML/NN based models might seem like a way to more or less circumvent copyright, but don't feel like there should be a blanket ban discriminating against potential intelligent entities that might arise in the future from more sophisticated technologies.
I also wasn't completely serious with my initial post. It is rather enjoyable to take an idea to the extreme and see what people's thoughts on it are.