Ortiz intentionally headbutted Floyd, that is wrong and he was penalized for it.
When the referee restarted the fight, Floyd made every indication that he's accepting Ortiz apology, even barely touching their gloves, but suddenly dished out a sucker punch knowing that Ortiz is not yet poised to defend himself.

Isn't this Floyd the same guy who demanded for a random drug test, TO EVEN UP THE PLAYING FIELD? This isn't even a fight between two equals. That sucker punch is legal but a sneaky move done on a defenseless underdog.