If missing turns into a paid industry then game companies will start cracking down on it, because then it becomes profit based on their work that they didn’t earn.
Whereas now when it’s free, it’s just passion projects by hobbyists who really like their game. It boosts their sales but it’s not like there’s extra money to be made in licensing deals.
If you allow what this guy was doing, you pervert that. It becomes an industry. It becomes competition. And it sets a legal precedent that if you let one guy get away with keeping all the money he makes, no one else needs to be held to that standard.