Can someone explain to me why it is when a competitor pushes another competitor out of the competition area they receive a warning even if the other guy is backing out? In most if not all grappling arts the guy backing out would be the one penalized, not the one pushing (who in most arts would be rewarded.) The referee tells him to circle, but shouldn't it be up to the person retreating to circle?
Normally there isn't any warning. You usually get a warning if you retreat out of bounds.
Warning is usually given to the guy getting pushed out if there are takedown attempts, in which some cases result in an advantage. However, if the guy pushing, excessively plays meathead sumo and does not do anything to attempt a takedown, this can be considered a form of stalling. Sure there is a grey area, but it's pretty clear if a guy is using wrestling/judo or just being E-Honda.