They have blocked both signal and simplex access...worry about blocking a niche application like simplex...from my point of view is that they have studied it and realized that it works very well.

Important because simplex does not depend on a third party you can have your own infrastructure. 

 Doesn't really mean much if the tool is rendered useless because of it...

Radio, it always comes to radio & IRL comms in the end. 

 The core routing & switching is their infrastructure, skip it. 

 It doesn't specifically mean it's private, but it's an indication that Putin believes it provides a level of privacy that is simply unacceptable to Russia. It's almost like an endorsement.