As soon as the moan that was decidedly laced with pleasure and not pain rumbled down the think mental link, Xavier cut the connection and slammed sheilds around Jean's mind to block her from all thoughts until the boy stopped his shouting. Granted the girl was old enough to know what sex was and possibly even listen in on others while they had it, but the mixed signals painted a very strange and twisted picture.
There were several possibilities. The first and foremost, because Xavier's mind simply went for the worst senario possible, was that the boy and Creed were doing a very strange sado-masichistic game that for some reason that even he didn't want to linger on included bringing the child's father into it. And Jean really, really didn't need to be witness to that kind of kink.