It is not "us guys", it is just this one guy. It is grating. No, there is no legal reason he is doing it. It's a reverse psychology play to get people to PM him about his indicator.
In Israel they were few cases of lawsuits , when some one showed/published his trading system (he should have a consultant license, and I don't have one), and people used the data for trade, so I write this disclaimer for my security only. if someone wans to try this system, be my guest.