Maybe you can dangle the carrot of not having to flush the spider logs all the time before him. LOL
It is always possible that admin does want the google and other spider exposure. On our forum we let them go about their business for several weeks after it had been set up originally and then shut them out. Main reason was that despite all efforts google still managed to get into the member profile section and some had posted their email so it was visible also to non-admins. Bad move.
Also, somewhere I noticed that you had made a post about deleting spam and spammers. Is that much of a problem? If so, I'd suggest you register with
and get an API key that can then be used to make autoqueries of IP, email and username (not much use but it can be done) when a new member registers. One hit, member is auto-referred for admin approval, two hits and pop goes the weasel, meaning, instant ban and IP blocking. The one hit can be adapted, ie. if it is the IP that fails the check, instant ban, email can always be abused.
Thought that might come in helpful. We've reduced spammers by roughly 98%, the 2% that slip the net... well, nothing is foolproof but this one is pretty close.