Losing is never an excuse for a display of poor sportsmanship.
The losing player in this table tennis match apparently had a big problem with the referee. After shaking hands with his opponent, the young competitor pushed the ref out of his seat.
The ref certainly didn't appreciate the shove. The two engaged in a brief staredown, but the losing player walked away to put an end to the situation.
It's not clear from this video if something led to the shove, but it is hard to fathom how something like this could be justified.