How does All for One Impact Recoil quirk works?
to completely reflect the impact


From where did you take this information? According to the Boku no Hero Academia Wikia the physical impact gets reversed, but not "completely reflected". 

So, it wouldn't turn the user invincible, because the user is still to some degree affected by the attack (as written in Boku no Hero Academia Wikia):


  However, this Quirk does not seem to cancel the impact completely


That is probably why All For One uses Gran Torino as a shield instead of taking the punch himself.