For years the Department of Homeland Security has said that if an alien wants to buy a bunch of EB-5 visas, for the alien, the alien's spouse, and all their kids, the half-million had to belong to the alien and that person had to prove that it had been obtained legitimately. Borrowing the sum was a no-no, just as getting the money in the drug trade, or from a sanctioned Iranian bank, was disqualifying.
Seems like a reasonable position to this non-lawyer. Buying visas with your own money is controversial enough, but buying a bunch of them with someone else's money? That should be out of the question.