So how does that affect the defense? I looking at the potential for a qb/punter only "8" yards back taking the snap and throwing a ball to an outside receiver that the defense is trying to block thinking it's a punt and getting an easy PI call.
The Rules Committee can't help folks be smart. If the player in "shotgun" is only 8 yards back, by himself, this is not a scrimmage kick formation. Defensive backs need to be as aware of how the ball gets into the air on this down as much as any other down. Team A can - and do - fake a punt a throw on 4th and long (with the player receiving the snap some 10-12 yards deep). This would be no different regardless of where the 'shotgun' player was positioned at the snap. That's why the Rules Committee created the rule absolving Team B of PI fouls when, from a scrimmage kick formation as defined, the apparent kicker instead throws the ball high and deep to simulate a kick, in hopes of getting a DPI call. The pass isn't illegal, but it removes DPI. A real risk for A, because it will probably fall incomplete, and go back to the previous spot, B's ball.