If you go to this user's page on Moodle.org:

http://moodle.org/user/view.php?id=142116&course=5

You can see a backslash escaping the apostrophe of the surname in the page title in the window bar, the breadcrumb trail and several other places. The name in big letters at the top of the page displays as expected.

If the user has actually typed in a backslash and the apostrophe (possible though unlikely) then it should be displayed everywhere, if not then it shouldn't be getting added anywhere.