Oh bid deal. So his site will be down for a few hours. Who hasn't had downtime? If anything this should be looked at as positive downtime as you have to have a successful site to run out of bandwidth with the exception of hosting media obviously. It's also in his hands and he can bring it back rather then a hosting provider when you haven't a clue what's wrong or when it will be back.

I've seen webmasters around here make far greater mistakes and fools of themselves.