He didn't.
Also eToro is still the most trustworthy of all the possibilities to short BNB which is kinda telling.
Most trustworthy? Tell me the metrics you use to determine if a platform is the most trustworthy. Personally, I don't like how brokers like Etoro operate. They have far too many limitations for retail traders, including subjecting them to tedious KYC verification.
I would rather use another crypto exchange that has BNB perpetual futures listed on it. There are quite many around.