Well, no -- it is not good enough. I did quite a bit of research about that comment, because it seemed to me that it would be highly unlikely that Bush made such a remark. I googled and read everything I could find and it seems that of all the people there only Shaath seemed to remember the remark (which can be translated several ways into english from the arabic) and no one else could corroborate it. Bush denies ever saying it, and no one with his delegation heard anything like it.
Shaath himself later retracted his statement.
My conclusion was (and is) that the comment was never made.