Legally nothing wrong with this, but if the choice is between asking permission and not asking permission then I would want someone to go with the first one just about every time, if only because using a forum handle that may still be in use or used across multiple media sites could potentially open that person to unwanted attention. The likelihood isn't high, but really the only thing you need to do to make it practically zero is not include the handles.
Would that count as lack of attribution though?
Would that count as lack of attribution though?