Turn off airdrop for non contacts? Turn off airdrop? Pretty misleading of them saying every time you click share instead of share with airdrop everyone can see some info.
My guess is that the SHA2 of the phone number is used for exactly this feature, so you can accept connections from your contacts only (your iPhone most likely already has a SHA2 calculatedfor each contact phone number) and ignore the rest.
Your phone will probably broadcast its hash in that scenario too.
Yes, very much so. It is also a mass generalization and a complete falsehood when the author makes bold claims like "Gen Z is using AirDrop to cheat". But they seem completely fine with their extremely generous claims.