I can only assume they see it as a double edged sword. Rights-holders (read: publishers, labels & studios) would have the power to sue here, not creators (read: artists, musicians and filmmakers).

These rights-holders also want to use AI so they don’t have to pay creators, so while they don’t love that other companies are making money off their content, they’re more just mad that someone else did it first before they could exploit their own content in the same way.

Sue and set precedent, and they might accidentally make it impossible for them to turn around and do the exact same thing.

Entirely speculation, but it’s the only thing that makes sense to me.