Thanks, you make some good points.eBay hates that type of behavior. Good behavior will be rewarded. Threatening you may be enough on its own for eBay to rule in your favor. Be reasonable and careful if you are going to continue to communicate with this seller (which I recommend you don't do).
Other things eBay considers is how much you buy and sell, how many cases have ever been opened against you, and your feedback score. eBay is very protective of all buyers, but it also is somewhat protective of anyone who makes them a lot of money, i.e. big sellers or buyers. Small sellers not so much. They can afford to lose small sellers who cause them problems.
Yup, I'm totally backing off messaging him. And I have an essentially spotless background on EBay, including a good experience selling you an item