It’s fair to ask the question. But as I said in my other post, I am almost certain that it is brand protection. It was a lazy way of saying that players can’t play in a US Open 9 Ball event or anything that is similarly titled. For example, if someone were to start an event called the "United States of America 9 Ball Open Tournament", that would likely be covered under the contract because such a title is trying to echo the "US Open" title. And yes, nothing like that currently exists but it's better to have that in a contract before there is an issue than play damage control if something were to come up. Pool does have a history of rival professional tours and world championships. Similarly, I'm fairly certain WST players have a clause in their contract that they can't play on a competing professional snooker tour even though nothing currently exists.
Hopefully, this is explained better by Matchroom at the players meeting. I really don't think they are trying to run other events and tours out of business because there is nothing to gain from it at all. These tours do not compete with Matchroom for sponsors or TV time. It would be like the UFC trying to run a regional mma promotion out of business.