Can usernames violate trademark law?

We got a legal threat this morning from FamilyPants.com because a user on one of our forums chose 'FamilyPants' as their username. They're upset because Google (and only Google) puts the user's profile on the first page of results for "familypants". I would think this is considered fair use. Link to the email posting on the offending forum.

read more | digg story