You seem to be under the impression that the Glazers are ruthless bastards who exploit the fans’ nostalgia and sentimentality for commercial reasons. And there’s no doubt that it’s useful to them.
Letting a culture of cronyism develop in an organisation is usually a sign of weakness and complacency, not one of hard-headed ruthlessness. And I’m not sure they would want empty stadiums at all, even though in the greater scheme of things it wouldn’t cost them a lot. Much of the PR is built on the illusion of a “happy family”. They aren’t going to want to lose that; hence why they re-signed Ronaldo.
They also wouldn't like an entire half where the fans sing songs about how shite the Glazers are and then the second half how shite the manager is. You need to do that despite results, you don't celebrate if we score but boo. At the end of the day fans are unabling them by being fickle and celebrating small events and ignoring the larger picture.