It doesn't, just like it doesn't protect ts from drawing the artwork in the first regardless if he being paid to do so.
In this comic/art world we all rely on good wills of these companies.
And these companies in turn were hold favorably as a return. They are, after all, wouldn't want to draw the ire of their core fan base.
As for youtube video, fair rights is also a good will from youtube and the companies involved.
As long as you are not being blatant about it, this fair rights is applicable.
TS is like these IP company, but without good will, whom overzealously protect his IP.
But he is currently at a worse position since he doesn't have the right for this IP in the first place.
you can use all these words about goodwill, but simply using the artwork exposes ts to litigation risk - something which the youtuber has no right to do. the youtuber himself can get away by claiming fair use but he leaves ts holding the bag.
ts has a right in reporting it (although he would be wrong to profit from it) to protect himself. its like buying a car for private use then someone else uses it for commercial purposes - you dont get any profit but you sure are liable to getting fined. the logical thing to do is to tell that person to stop doing it.