They are suspicious. Well, you would be, wouldn't you? Bobby points out that this isn't really any better than, say, Emma Frost taking over their tuition. And Magneto is really starting to wonder about what he's let himself in for.
Fortunately for him (but less so for Dani), he soon gets the opportunity to prove his worth to his charges. When Dani arrives back having nearly been assaulted (we don't really have to read between the lines to deduce that's it's an attempted rape), Magneto goes looking for the perpetrators, and here demonstrates the difference between him and Xavier.
Professor X would have mindwiped them, or something. Magneto just puts the fear of Magneto into them, and they decide that confessing to the police would be a really good idea.
This is some good character development: Magneto is protective of the children, which is entirely in line with his revelation in #150, but useless at management or leadership skills (he's been a solo villain since the break-up of the original Brotherhood in the 1960s, and he was a fairly imperious and ineffective leader of that). Here, he learns that he needs to be loyal for the kids for them to be loyal to him - an important step forward, which combined with his missing of Lee make him appear to be an actual rounded person. Please don't screw this up, Magnus. But I question the point of having a story with an attempted rape and then somehow making it all about a man. Can we not find something less gratuitous?