You'd lose. No such rule or law, and has nothing to do with immigration enforcement.
Especially with Americans, opening an account is just a pain in the a** for the bank. Why bother if they're here for a couple months than they're gone? Money loser.
But ultimately, this is the individual bank's decision.
An agent can definitely grease the skids, and there is nothing wrong or illegal if you use one.
You have $10,000 in the bank and a $1500/month social security payment.
The average rent in America is $1500-1700 per month. Nevermind all the other expenses. Never mind all the hoops to jump through to get an apartment.
You can get an air ticket to Thailand for $1000.
You'll be homeless in the USA in six months or less. GUARANTEED.
So your answer to the guy is, buy a tent and join the homeless because you never know when you'll need your medicare.
But in Thailand, you can rent a nice condo with AC, pool and gym for $300/month and you have $9k in the bank. You may never, ever need a hospital.
And you're going to tell that guy to stay put and join the homeless campout TODAY just in case he ever needs a hospital?
Absurd. The flaw in your reasoning is that you think it is better to have health care at any cost up to and beyond homelessness "just in case" than it is to have a house, good food, and personal safety.
And if you think most hospitals in the US will give you appropriate care without resources, you're even more naive than you look.
Has it not occurred to you that the whole 800k requirement was specifically set up to allow the agent/bank/immigration to make additional profits from retirees?
The government could stop it all literally tomorrow if they chose. Yet they don't. I wonder why? Because this is Thailand, and things work differently here.
For perspective, just across the border in Cambodia, a one year multiple entry retirement visa is $290, no bank account required, no 800k baht deposit required, no 90 day reporting.