It doesn't matter if it's consistent with the way ever single offence in the history of the game has been judged, it's consistent with how Dean has decided to ref this game. Go in swinging like that a couple of minutes after the initial yellow was just incredibly stupid and Dean was entitled to get the second yellow out. No problem with his refereeing there, all the blame on Mata.
Dean hasn't booked anyone else for other trips, so not sure how it's consistent.
If Mata followed through it would be a stronger case, but he actively tried to pull out of the challenge.