Hi, Bob,
This is fun!--at least compared with doing my taxes. I agree; time to move on. The more you say, the worse it gets, even with 189 words of "plain language."
I'll think about that course in contract law you suggested--after I finish my current sessions for selective reading disorder.

Until then, my layman's impression is that among other elements required for a valid contract is "consideration", for example if you had agreed to refrain from posting ads on other sites that you would otherwise have had a right to do. Absent consideration, my view is that all you had was Tim's promise to display your ad for as long as he felt like doing so. Subsequently, you two entered into a negotiation: he made an offer, you declined to accept it. Again, no contract.
That said, Eric's suggestion is a good one: make the policy more explicit. We do a lot in soaring fairly informally. But Tim is in business so it's in his interest to avoid misunderstanding (although my impression is that he's coming out of this fray looking pretty good!). I apologize for being a little oblique in my last epistle. I intended to convey that Tim's "These ads are intended for..." disclosure was probably aimed at other commercial sites that might attempt to clone the ads on his site for their own purposes, not at the individual glider owner. [Hey, my selective reading disorder instructor has published a self-help book. Would you like a copy?]
Seriously, best wishes on selling your aircraft...and on finding a soaring vendor brave enough to risk his/her future reputation by selling you equipment for the new one. I'm not saying it's right that Tim hung up on you, but after participating in this discussion, I have some appreciation for why he might have felt obliged to do so.
Chip Bearden
ASW 24 "JB"
U.S.A.