If they are in the US on a work-permit, they have to follow the limitations of the work-permit. They are not free to follow the affordances available to people who are outside the US. For most temporary work-permits, owning a business is not permitted. The govt. wants the worker to work for their sponsor, not own a business. After one gets a GC (i.e. permanent residence), one is free to work for anyone, or start businesses.
That’s not actually quite true. You can own a business on a work permit, you just can’t work for it. Which is mostly a pointless arrangement, but possible.
This is a more accurate take. That you can own businesses, but you can't work for them without an appropriate work-permit. He was working for his businesses, which explains why he's in a pickle.
It's perversely hilarious to see people supporting fascism for its attacking other individuals, and then demonstrating zero awareness of how little regulation applies to capital crossing borders. It's a crab bucket, alright.