I like to believe this is where Takahiro goes to fully unleash the horny since he doesn't have Yuuki actually fuck anyone in Mato Seihei despite some situations/positions he's in are damn well implying it
Never understood the 3rd rate villain motivation of "The boss will like me if I kill the person they favor." It's so counterintuitive. Anyone with a brain cell can figure out that it will backfire.
Keep in mind that while favoritism means better tasks, more rewards and generally easier life/work it also means you can be elevated to pedestal in morning only to be send to prison in the evening. So the squidman becoming warden's favorite could potentialy pose some threat to Ruwaida's position and/or well-being in the long run and thus she is taking precautions. Also, 'eliminating' doesn't necessarily means killing.