I don't know if it is so much of a mandatory termination as it is there a plan sponsor any more?
It isn't clear to me there would be a plan sponsor if the person is no longer in a trade or business.
When the person is no longer engaged in a trade or business? And why would you file a Scheudle C with no income/expense?
I'm not sure the plan necessarily needs to be terminated if there is no business anymore. That I think is an interesting question. I'd be curious to see what everyone else says... I have never heard of a "mandatory termination."
No. This belongs in the Humor section. Get it??? The "investment advisor" actually advised the client on plan matters that go beyond the scope of investments. LOL. I get it.
Good Luck!