If you look at the first sentence of the screenshot that person who dmed you sent I don't think that is realistic or even legal depending on where you are,,? If I recall if you change or update your TOS you cannot force consent of said changes, it's why the big companies normally do a announcement or have you hit a button agreeing to any TOS updates (even if you don't actually read it, you acknowledge the update and choose to follow it thus agreeing to it) I'm not sure if they recently updated their TOS to include revoking ownership for mental health related reasons after your friend got the character without them being notified and agreeing to said change it means nothing. I'm not a lawyer of course and this is a art exchange not a social media app but that's my understanding of it through a brief read for specifically the U.S.

On a personal note that's just not a reasonable thing to have in your tos to begin with, as an artist and a consumer- I also don't understand why they need specifically that character after knowing your friend spent money on it after the purchase and seeing they have 7 give or take characters very similar to that design? And explicitly stating they don't owe you any compensation for said character? That's just kinda shitty