Did you read the OP (and the twitter post linked in it)?
If he sold his own funds, it wouldn't be a short sell in the first place. It would be just a sell, as what thousands people are doing on a regular basis every day. If you read the opening post, you would get an idea that it was a futures market where you buy and sell contracts, not actual bitcoins. The only way he could sell a futures contract without going short is when he bought it before and sold it later thus closing his position either at a loss or profit. In this case, it would be profit, not loss, since the price is going up
if you are trading shorting simple mean to buy back after selling, it does not really matter if they are your funds or not, it doesn't make sense to say that you can't short with your money
the same for going long
Stop spreading misinformation. And as far as I remember, this is not the first time you are claiming something you don't know or use your understanding which has nothing with the established terminology. Technically, if you sell something which you own, you basically close your long position in that, about which I wrote right away in my post. As I once told you, you may think up anything you please, just don't tell this as if it were an accepted convention...
Short selling (
from Wikipedia)
the practice of selling securities or other financial instruments that are not currently owned (usually borrowed), and subsequently repurchasing them ("covering")
Short selling (
from Investopedia)
Short selling is the selling of a stock that the seller doesn't own. More specifically, a short sale is the sale of a security that isn't owned by the seller, but that is promised to be delivered
Though I don't think anyone would be interested in your definition since it obviously interferes with the accepted one