If you do accept a booking request, bear in mind that he can also leave you negative feedback which you'll have to contact the mysterious AW Authorities to dispute/remove.
Generally, if I suspect someone is a timewaster, I just avoid/block/delete all their communication attempts and forget about them, cos getting overly involved just makes them more excited and likely to act in a way that's potentially damaging to your business and/or mental state. And I never use the AW booking system for anything (unless a client specifically wants to make a booking request) - setting your own confirmation procedure works just as well and doesn't put you at risk for getting spiteful feedback. I know others do rely on the system, of course, but I've heard too many nasty stories that begin with "He had great feedback on AW so I was really surprised when..." to do so myself.