Looked at the play again -- and now thinking this is legal. The scrimmage kick formation definition only applies "at the snap". If, at the snap, you have a scrimmage kick formation, then all the eligibility / numbering exceptions apply.
Here, though, they ARE NOT in a scrimmage kick formation at the snap. They move out of a FG scrimmage kick formation (7 yards deep), to a punt formation (no holder). Notice the kicker moves up -- and at the snap he is 9 yards (not 10) behind the LOS. Therefore, this is not a SKF by rule. Thus, no the requirements / limitations of 7-1-4-a-5 do not apply and instead the normal requirements of 7-1-4-a-3 apply. So long as Team A has 5 players 50-79 on the line out there to the left of the formation, then this is a legal play -- A46 is legal both by number and position (end).