It depends - but once that happens he is likely in the clear. The FCRA(https://en.wikipedia.org/wiki/Fair_Credit_Reporting_Act) states that once a debt is acquired by a new party, you(the debtor) can demand a proof of debt. If you don't get it in 30 days after the demand, the debt is null and void. If you do get it - proceed directly to small claims court and dispute it with all your documentation, and ask for an immediate bench ruling. There are precedents for this type of thing, and they are on the poster's side.

IANAL

Most cities charge <$50 for small claims court hearings too.

Can't you also ask to recover any court fees from the defendant if you win?

I love your willingness to be blackmailed.

It's not blackmail. He locked himself out of his account, and Amazon is erring on the side of caution before turning off services and shutting down accounts.

While it might be a nuisance to get a document notarized, it's not some extraordinary hardship. The policy is there to prevent abuse. If he prefers to let his bill go unpaid as a result of locking himself out of his account, that's his choice.

The point of humans providing customer service is that they can judge that in this case the account can in fact be closed without harm.

You shouldn't have your credit ruined for not wanting to give up your documents to some shitty company.

That's not what's happening here. Not paying your bills does rightly deserve a warning on credit reports.

Not paying your bills because you lost access to your own account does not change this situation. The same way as that having no income or car or phone or internet and can't pay your other bills doesn't excuse those liabilities either.

It's practical advice.