Mokuren was not one to get involved in fighting that she did not start, but she also couldn't let Geni get expelled before Mokuren could kill him. She had a gripe with him that far surpassed the petty dispute about wither or not he worked to free Faunus from human tyranny. So, when the shit started to hit the fan she stood up silently and moved over to the group of people that where shouting. That said, there was no way she could stop him with Sarasagi when he leapt into action and prepared to crush the guy's head with his sword, the gunshot going off and making it even more unstoppable. Which is exactly how Mokuren liked her attacks.

With unnaturally lithe grace, Mokuren sprang from where she was standing and managed to arrive in front of Ivan - who was not exactly innocent in this and would get a clout later from the fox girl - and prepared her Semblance to reflect the incoming attack. The idea that it would be Geni taking the hit if anyone was not one that entered Mokuren's mind, she was just trying to stop some guy getting murdered. And hopefully the impact of a sword strike would be less lethal than an actual sword strike.