I mean, their concern is not completely unwarranted.

Yes we know, a smart person googling their name and getting to your fic would easily figure out they are not related, but tbh the average person is not that smart. Plus, employers who look up peoples' names online won't go deep enough to clear any misunderstanding. They will just look at the first result and see it's something they consider inappropriate, and whoosh, there goes your interview. Especially if their name is so uncommon they have trouble to convice people it's just a coincidence.