There are some restrictions on using the funds, which can result in prohibited transactions. The concept itself is allowed. It is expensive; we used to laugh about it being called "ROBS" for a reason. It's sort of like a backwards ESOP.

This is not really Financing. It is an investment, and like any risky investment using retirement funds, there is a lot of due diligence to be done. The minimum is $50,000 as I recall, and the fees can be very high, not to mention that now you are running as a C Corp, which is not cheap, either.