Gee I hate people who expect sellers to be on their phone 24/7 & responding to messages instantly. I bet it is a one way street and they wouldn't be like that if selling.
As you know, this is a difficult customer. Even given the guy paid immediately, no normal buyer would necessarily expect to have the address and pickup arranged within the hour. This person is all about themselves and what suits them. Just the fact they offered you less than the advertised price showed a sense of entitlement.
I think it is possible they overlooked the cash only bit in the flurry of negotiating down or else felt that (like the price), terms in the ad were optional.
I could be wrong here though but I was under the impression sellers had to offer buyers a payment method other than just cash. That a paypal payment, although annoying, would be perfectly 'legal' ebay wise.
If that is the case, there is a possibility ebay may leave any negative stand, although you could always contact ebay and say you cancelled because of harrassment as they were accusing you of being a bad seller within a couple of hours, all because pickup was not possible in that time frame.
If you do need to contact ebay, I'd be stressing that point, that they didn't allow time to arrange pick up, rather than just saying you wanted cash.
If the worst came to the worst and firstly the buyer gave a neg (which may not happen) and then ebay refused to remove it (which may not happen), then what I would do in your shoes is reply politely and explain you had 15 messages in the 2.5 hours after a pick up sale, demanding immediate pick up with no attempt to arrange a mutually agreeable time.
Not all buyers check feedback for starters and for those who do, if they can see a buyer has been unreasonable, they will disregard it. Your other feedback record is good enough to stand up to one wacky neg, should you get it.
