Please don't take this personally clarry but I really don't understand why you wouldn't at least give the buyer the benefit of the doubt.   At this stage they have done nothing to indicate they are suspect, they simply prefer to keep thier purchases private, IMO privacy is something we don't get enough of on the internet, so I wouldn't be hiding that against them.  For my part, I don't block anyone unless and until they give me first hand reason to do so.