“We can steal people’s copyrighted content but we can’t let you see it for yourself.” Outside of privacy (leaking PII), the above is likely the main reason. Someone could have invested a lump of money to scrape as much as they can and then go to town in the courts. The terms that prohibit it are under “2. Usage Requirements” that restrict reverse engineering the underlying model structure.
Leaking original data would expose the company to direct copyright violation lawsuits. Changing T&S is simplest way to stave the legal risk exposure, buying time to implement technical remedies. As ridiculous as it may seem, they're doing the right thing.
“don’t touch the unsecured, loaded firearm that is sitting on the counter, that might be stolen, maybe even got a body on it, don’t look too close, or you can be kicked out of the club for not following the rules”
so if this is what the right thing looks like…