It seems like his argument is that putting access to valuable accounts on your phone is a bad practice, because if your phone is stolen at the club after the thief watched you enter your code, then the thief can get at your banking, brokerage, crypto, password manager, etc.

But that argument doesn't address how passkeys somehow make that worse.

Sure, if you don't want your valuable stuff stolen, don't put it on your phone. But that's a problem whether you use passkeys or passwords or passwordless links sent to your email or SMS.