Im thinking that since satori can read minds she might have mistakingly thought that she herself has to go to the restroom that is the only way this would make sence to me
I'm pretty sure Orin's thinking those thoughts on purpose, even though she doesn't have to go, so that Satori will be bombarded by them and have to go to the bathroom herself. In short, Orin's teasing Satori in her own way.
The "Just as planned" look on Rin's face at the end gives it away.
Uhm, actually, I didn't realize that the balloon was coming out of the cat. I changed the translation to something more literal now. Any interpretation is possible.
Actually, I think it still works translated idiomatically. Whether Satori's trying purely to find a spot where Rin can relieve herself or if she's developed a need of her own, she doesn't want to put Rin down and risk a mess, so the result is the same.
