"A one-participant 401(k) plan is generally required to file an annual report on Form 5500-EZ if it has $250,000 or more in assets at the end of the year. A one-participant plan with fewer assets may be exempt from the annual filing requirement."

From the IRS: https://www.irs.gov/retirement-plans/one-participant-401k-plans

I wonder who will be doing the compliance monitoring, the reporting, etc? This broker seems like they don't know this process.