I'm not sure how you (your wife) can dismiss this totally out of hand. They could have originally intended to buy some of the club's shares from Madrox, so a SPV was required. The fact that SD doesn't want to stay on now, and that there is now a loan between the american company and Madrox, means it would be much tidier for the american company to takeover Madrox directly. Otherwise, that loan would need to be dealt with before SD could sell to FPP.
Madrox has hardly any history and is merely a holding company - I don't see any increased risk of the american holding company becoming shareholders of Madrox rather than putting another UK holding company in between. They already have separation via the american company. There is no tax advantage to putting another UK holding company in between because if, when FPP want to sell, they want the capital gain in the UK, they sell the club's shares, if they want the gain in the US, they sell the Madrox shares.
It could also be a tactic to get SD to panic thinking that they are pulling out. It only takes a quick form submitted within 2 months to cancel the striking off of FPP Sunderland Ltd. Even if it is struck off, it only takes a day or two to register a new company.
I'm probably clutching at straws, but I haven't fully given up on FPP yet. I just hope we get some clarity very soon so we can move on.