Quite simply there are multiple factors at play here. Do you force 2FA on almost everyone and reduce hostile account takeovers to negligible? Do you allow for no 2FA and permit the homeless use case?

I think Google faced a trolley problem and made the right decision. You need a different tool "homeless mail" for them.

It's Gmail. You don't have to use it. There's a lot of mail providers out there.

Whatever, if this guy won't set it up I will. I'll stick a 20 msg / hr, 100 / day limit on it and call it a nice anti-spam day.