You never know what people will listen to and what they'll ignore. And not saying they were wrong to be frustrated when not being listened to, but also think they made too many assumptions as a mentor in the first place. Mentor's are meant to guide and teach. Patience is kinda on the job description. While it's great to get those energetic players who will listen to what you say, you're going to run into twice as many who don't give a care. Teacher's can't exactly kick a student out of school because they don't listen (unless they literally did something wrong). Yes frustrating, but the other newbies had to suffer as well. In a normal DF, I'd say right call. In a mentor roulette, i'd say a bit quick to jump ship. She literally signed up and queued for a roulette with potentially inexperienced players.
It's not that I don't feel bad for the situation. It's that I think those who sign up to be a mentor need thicker skin. You literally signed up for helping out a few good students and a majority of those who don't care.