I don't think it's correct to point to the drinking MO or a conspiracy to suggest that Mike was allowed to fly as a fiddle of some sort - he flew Nimrods whilst significantly affected, and was genuinely passed fit to fly regularly by a variety of people, over an extended period of time. That the paperwork trail was not completely as it should be is not a sign of devilry, in any walk of life perfect paperwork is the exception rather than the rule.
With respect I think - were I an MO - I'd be reticent about grounding somebody for a condition that had been repeatedly tested over many years, with the condition being described as (essentially) stable...
Mentioned elsewhere (can't recall which doc now) several dozen US pilots with this condition had been reviewed and the majority passed fit to fly - now you can argue that anyone significantly affected by AS should not fly, or should not fly without a qualified co pilot, or whatever you wish... but at the time of this accident such a rule did not exist.
My belief is that NOBODY ever realised that Mike could be incapacitated (or killed) by a relatively minor impact - so the potential for tragedy was not appreciated until after the event....hindsight is, as ever, 20:20 vision.