More Rule Book / Case Book language issues IMHO. The bottom line here is we're going to tell the B player calling signals to move back before we make the ball "RFP" with the either the old (whistle and chop) or new timing rules (U leaves after placing the ball). Also, an A or B player touching/entering the NZ while getting aligned prior to the snapper having his hands on the ball is not going to get a flag based on our guidance. Probably a quick talk to reminding him to stay out of the NZ.
That being said, once the players are set and the snapper has his hands on the ball and we're "ready to go" any NZ encroachment by either team gets a whistle and a flag.