You must be absolutely insane to think a true businessman would even entertain the idea, nevermind sell a club like United.
You don't need a PhD in Business and Management to know that you don't sell a business that is profitable. These guys are not your average entrepreneurs that own a small coffee shop, they're top dogs that have made a fortune by being bloody smart, they don't sell one of football's mammoths who, financially, also happen to be right there at the very top.
These guys don't just sell because fans fly some banners by an air plane, they don't care about this, they use their brains when conducting business, not their soul, they are ruthless and don't care you are upset for a loss away at Bournemouth.
Just look at Abramovich - can't attend matches, can't even visit the UK and there is no sign he'll do it soon. Still he won't sell this kind of profitable business because these guys put money before everything, don't care if they cannot attend matches or if anyone flies useless banners as long as the business in growing which is happening at both Chelsea and United.