Because they're in denial and it's mildly amusing. Like the Amish, but if it was just a silly preference instead of a religion.

This is such an interesting take. Upthread, there's a discussion about how the policy isn't really what the policy says, and that if you read between the lines, it really does allow AI use. And here's the opposite take, that the policy really does mean what it says, and if you're "reading between the lines" you're being anti-social. This is why making the CoC very clear is a good use of time!