A few general thoughts:
1. Everyone are vulnerable to protests, in particular the Glazers. The problem is that mostly protests at and around OT haven’t impacted them.
2. Any kind of concerted protest from a vast MUFC fan base could have a major impact — if it targets something that can be impacted.
3. Protests does not have to be direct. It is — much — better to make an indirect protest that only partly regards the subject you protest against but that is impactful. Like if China has an issue with Sweden, they attack H&M and Ericsson, not the King or country per se. Your friends problems become your problem. Etc.
The Glazers are seen as leeches in the UK but they are pretty anonymous in the USA. I Googled “Glazers” for news the last 24h a lot during the early period of the sale process and they are fairly active, pop up at fundraisers and they do a lot of small time business.
I think that they would be very concerned if their reputation in the US/Florida even remotely was as tarnished as it is in the UK. If Utd fans created a big problem for someone in the US — it becomes a big problem for the Glazers. But to make an impact — it must be well organized.
4. I wouldn’t say disrupting games are useless — but I think hitting the Glazers on their home field is the way to go.