Merchants the man!
To those that didn't watch the right our read the results, what happened is that ortiz headbutted mayweather, who was very clearly winning and controlling the fight. The ref temporarily paused the fight, and docked ortiz a point.
Ortiz attempted to apologize while the fight resumed, and mayweather hit him while his guard was down. Ortiz turned to the ref to see if he was going to do anything, and mayweather annihilated him while his head was turned.
The fight had resumed, so it was completely legal, but very poor sportsmanship. Made worse when he got into a verbal slap fight with merchant.