Chinese sellers? Really bad news. This is what killed Ebay's credibility. I once was on Ebay just surfing for costume jewelry - I wanted to see what I could get for .99 cents free shipping from China so I ordered a bunch of things - one item from each seller. Well first of all - they all messaged me - how come you only ordered one thing ? We can't make money that way. I responded - you shouldn't be offering those items at that price then. Well when they came - they all had the SAME dispatch address. Yes. Dozens of "individual sellers" all working as agents for one manufacturer. When I complained about that to Ebay because then you weren't even allowed to have more than one account yourself - and here was in reality one manufacturer - probably backed by their government - with dozens of and probably hundreds of sellers - and some were based in CA and TX but still getting their stock in China. Ebay said nothing preventing all these people from "getting" stock from the same place - and of course - ignoring that they are selling things they didn't even have which is why so many orders went missing or unfilled after the sale. They rack up thousands of negative reviews, then just close up and open under other names. One seller even had multiple stores himself because I even asked him - is that you too? And he just said oh yes - not even trying to hide it. So they were all able to avoid the listing limits plus the glut of their merchandise destroyed any base for any small seller trying to get their stuff seen and no US seller could compete with the 99 cent free shipping promos that was attracting their customer base. Etsy did the same thing just before its IPO to artificially increase its inventory but what I hear now is the % of actual sales per shop has really tanked. And so it starts at Tradesy. They obviously just bought out Shophers full on without being discriminating about what they were migrating over. 
). I would call Tradesy about this buyer and explain why you had no choice but to cancel. He seems like an awful buyer. I had a guy buy a purse from me. I appreciate him buying my purse. 
Sadly, your buyer is not playing with a full deck of cards. Oh, I would make sure the sell said cancell because the buyer demanded it. 
You might have been saved from another bad buyer drama from him. I wish you could block him too. 
However, I do point out to buyers that they are shopping from a closet items that are loved and owned by the seller. 
now I'm off to :banned: banned island lol