It's a "cover up" if you'll pardon the pun. :-) Seriously, I think:
* It was minimising the impact of Freddie's illness (though it wasn't that visibly severe at that point).
* It was making a (perhaps "protesting too much") point about unity.
I'm not sure that the miracle cover was actually minimising the impact of Freddie's illness - after all in the videos for Breakthru, I want it all, Scandal, the Miralce, Invisible Man, Freddie actually looks fine. Also, it wouldn't be the first time that Freddie's face hasn't appeared in full on an LP cover - Magic, Hot Space, Flash, Live Killers, Jazz, News, Races, Opera, Queen. There are probably others I've missed.
Without wishing to be guilty of revisionism I knew in '89 that something was up; I didn't have any idea what. And I'm damned sure they knew that, too.
Doesn't mean I'm right and it was deliberate manipulation of their public.
And sorry for being ghoulish. :-(