So we have our answer then. 46 has established himself as the snapper when he moves his left hand from his thigh, below his knee, then to the ball. At that time he is the middle man of 5 interior linemen and by definition a numbering exception. By rule therefore this is a foul. The remaining 4 interior linemen actually leave after 46 became the snapper by rule.
That being said, the timing here is close, but stop action frame by frame IMO makes it clear he's the snapper before the other linemen leave and we've always been advised that on trick plays when in question it's a foul. IMO he needed to wait until he was actually on the end of the line before he started his motion down to the ball.