Royce was fighting Hidehiko Yoshida (1992 Olympic Gold Medal winner in Judo and 2000 World Judo Champion).
The following is not to be taken as pure fact - until we see the fight for ourselves we can't really say what happened for sure.
Yoshida was attempting a pathetic gi choke on Royce, this didn't need much defending. Yoshida then looked up to the ref and said Royce was out, the ref then stopped the fight.
As Yoshida was standing up Royce was already pushing him away and getting up in disbelief.
It was obvious that Royce was never in any danger posed by Yoshida's submission attempts - obviously the whole Gracie clan went mad and are currently in talks with Pride officials to have the referee's decision changed to 'No Contest'.
A re-match is sure to follow, only time will tell.