If this is accurate, it finally explains something I've been asking about for years: The loan is paid back after the step-up in basis. That's the loophole. If the loan was paid back before step-up, the estate would still have to pay capital gains tax.
It's disheartening to see so much thought and deliberation going into an obviously toxic idea (taxing unrealized gains) when the obvious solution (removing the cost basis step-up when assets change hands) is being ignored.
Inherited wealth is the least earned, so it should be politically palatable to change this. But presumably because such a change would acutely affect the people who make laws in the country specifically, it is never seriously considered.