The only thing to watch out for is how much Jim keeps poking Nintendo, he did put out a video advocating for people to pirate their games. For reasons people already covered it is doubtful that Nintendo will come after him for the shirts.
Jim does have an understanding of copyright and how to exploit the system.
He even came up with the copyright deadlock. He did a video on it where he explains how he uses two different copyrighted works to prevent the companies from getting revenue off his video.
I will let Jim explain it himself. This is an older Jimquisition from 5 years ago so it is watchable.
However, if he keeps pushing and gets on Nintendo's radar I would not be surprised if it would be an intentional move so he can have an excuse to play victim. Either that or the drugs are frying his brain or maybe both, but he does have a history of dancing on the line.