I feel like if you get 30% of a deal you should be a valid target in a lawsuit about that deal. Scam app steals your bitcoin? Apple is on the hook if they want to get the middle of it like that. They can sue their business partner to recover.

Something smaller, like under 5%, close to the cost of providing the service, would be more like a "finders fee" on the other hand shouldn't have such a duty.