YOU choosing NOT TO DELIVER, once I paid already, is the cause for all this bullshit. I am not letting you keep a single cent in profit as you deserve nothing other than that treating customers like that. Your waste of time cost me 10x the amount you owed me, but I would rather have you learn your lesson and treat your future customers correctly instead of just letting you do whatever the s*** you want.
It's customary that the seller refunds the amount received - network fees, so the amount he sent back is acceptable.
I recommend you relax and try to understand reason instead of constantly attacking and assuming everyone is out to get you.
What he told you is real, the fee stated is correct, because binance takes a big chunk out of BTC withdrawals. It's his problem, as he chose to use binance to receive your payment, and he should have received it in a normal wallet instead.
However, he was willing to find a compromise and send you a different crypto with a lower fee (current median network fee on a normal wallet is 2-3$ and on binance it's around 15$) and since you did not want a compromise and demanded the BTC, he sent it without even waiting for my response.
I consider this matter settled as the logical amount for a median BTC fee was deducted.