Board Thread:Episode Discussion/@comment-1599757-20151212162645/@comment-410526-20151212172744

Arkantos95 wrote: I do have to wonder why they wanted Yang out of comission so bad that they'd be willing to have Mercury break his own leg. Because Aura or no, that guy is going to be out for a while, and Yang honestly feels like she'd be the least troublesome of Team RWBY to deal with. I think it was less about them getting Yang out of the picture and more about the reaction of the audience. Note how they cut to the audience all booing and the Grimm taking notice in Mountain Glenn and such.

It's worth remembering that the Vytal Festival was set up after the end of a devastating war between the Kingdoms. The Festival is a symbol, it's all about good-will between Kingdoms and sportsmanship and camaraderie and all that good stuff. Yang (apparently) violating that spirit would actually have a lot of deep-running consequences. It'd cause people to be angry and upset, and that would attract Grimm.