They didn't actually stop him, by the way, this is just re-writing history. I have a copy of Dangerous Journeys right here. It doesn't seem very "stopped" to me.yep, because he could not fight them. Had he had a different name they would not have bothered though, I do not think we have someone with that name recognition now
TSR made some sweeping and wild IP claims against GDW who were publishing Dangerous Journeys. If they had gone to court, they would have lost a huge number of them. That's not a maybe, TSR would have. They might even have lost all of them, because they were extremely far-fetched stuff. In modern courts it might even be suggested that those claims were so bad that they were an abuse of process and the judge might have censured TSR and the relevant bar might have censured the lawyers bringing the case.
Anyway, they got to court and GDW decided they couldn't make enough money off Dangerous Journeys to make it worthwhile to fight WotC, so they did an out-of-court settlement.
If Dangerous Journeys would have been more likely to make real money, or if legal crowdfunding had existed back then, or if it was in a modern court, the outcome would have not been the same.