Xavier lived by the creed that what a person didn't know couldn't hurt them. There was much he didn't tell his students, his X-Men. Much he was positive they wouldn't understand. In the case of Rogue, simply not speaking of her latest foray into walking the other side of the line would be the best course of action. Let her re-establish herself in the mansion and in a few months, should the truth come out, Xavier could vouch for her making a youthful mistake and then point to what had happened in the time between and make a speech on giving people second chances. All the good things the X-Men stood for. People might moan and groan, but they wouldn't hold the grudge for long.
"You should order a drink and I'll have the car pull around so we can go home," the Professor said with utmost confidence as if the matter were at an end.