You’re right. It certainly would be illegal and I believe they would disclose it if they were doing that.
On the other hand, lots of companies do illegal shit to benefit themselves. Who knows, maybe if Jagex thought they could get away with it they wouldn’t disclose it and they’d have a huge advantage.
I don’t believe that’s something that would ever happen, I don’t think they can tell. This is basically a what if sort of discussion. Obviously they aren’t currently doing any of that.