I'd love to see you try to enforce that license because it would only prove my point. You'd have to sue me; then I would point to the terms of service of this platform and point out that by using it, you have no license here.
Fair use though, only applies as a legal defense because someone asserts you stole their work. Then ONLY the court decides whether or not you used it under fair use. You don't get to make that decision; you just get to decide whether to try and use it as a defense.
Even if you actually did unfairly use copyrighted works, you would be stupid not to use that as a defense. Because maybe somebody on the jury agrees with you...
Fair use though, only applies as a legal defense because someone asserts you stole their work. Then ONLY the court decides whether or not you used it under fair use. You don't get to make that decision; you just get to decide whether to try and use it as a defense.
Even if you actually did unfairly use copyrighted works, you would be stupid not to use that as a defense. Because maybe somebody on the jury agrees with you...