The part of your quote I put in red... just curious, have you ever watched Bob or Daves' high speed videos of the shot? And, are you familiar with what a push shot really is??
The reason I ask, is because when two balls are frozen, and you shoot with a normal stroke, the cb will travel the same speed as the ob. Even though it is a good and legal hit. Now....if the balls have any separation to them, then if the cb follows at the same speed it is a surefire way to tell you double hit the cb.
A push shot is when you place your tip against the cb, and just push through it. Doing that, your tip stays on the cb for a longer period of time. Using a normal stroke, even with two frozen balls, the tip doesn't stay on the cb more than about .001 sec. No longer than on a normal shot.