A good summing up, slim. I'm also inclined to think it's around his drinking and his outspokenness, or some consequences of the two.
It's likely the GB are embarrassed by this business with AMIII, partly because of his previous high profile and partly because many of his other family members are still 'in good standing'.
I do think the GB could and should have said something about it on their broadcasting channel.
Agreed. They probably just wanted the issue to go away and so instinctively fell back on their 'don't ask, don't tell' policy that usually applies to the removal of appointed men, whatever the reason.
That also explains to me why they quietly announced his stepping down on the website, but then removed the announcement very soon after. They knew they had to inform people, but did it in as low-key a way possible and then pulled the plug on it when they started to get awkward questions from brothers around the world (and possibly also from exJWs and outsiders who watch their website activity).
It also explains why they're only gradually removing him from key images and videos. If they did it all at once, it would again be quickly noticed by the R&F and many others, and raise difficult questions to the branches.