The letter that Wimbledon have sent is ultimately meaningless and won't make any difference.
They say that the lack of positive cases is not down to luck, but there is absolutely no way they can support that. The protocols they have put in place are no different than anything we have done at Oxford. We have split the under 23's and youth squads all season, test several times a week, keep players in bubbles and have done everything practical to maintain infection control should someone test positive. Yet we've had at least 3 "outbreaks" that have affected players (pre-season, Wigan away and Wigan at home).
This is impacting every club on every league as well as every other profession. Anywhere people work closely with others there is a chance of having spikes in infections, and Wimbledon will be incredibly lucky not to have their own squad affected at some point.
They ask for 5 substitutes to be used per game, which is perfectly reasonable and something most of us would agree with. But the reasoning to ask now doesn't make sense. If clubs are unable to field 13 including a keeper, or whatever the threshold is, then increasing playing squads to 18 will only lead to more games getting cancelled. And its difficult to know whether they support FA Cup replays or not.
Either way this letter will be filed under Bin at the FA and we'll carry on as before. That's not to say that I don't agree Wimbledon, but public health will always trump disgruntled football club in these situations.