Haig, a true war hero was lambasted over that and never truly recovered politically. He knew that Bush was in charge while Reagan was down. As you said that was his concern, as I recall last years episode, the KGB agents were also thinking this was a coup attempt. It makes sense they would think that from their perspective. They weren’t used to our stable democracy. Coups were rife throughout their history so naturally they assumed that we had coups also.
That is one of the reasons I find this show so interesting. I think they truly give us the enemies perspective on the cold war. I find it fascinating to get a glimpse into Russian thinking at that time.
You might recall this; the Ruskies tried to blow up Haig when he was the SPAPE commander (NATO), they managed to blow up the wrong vehicle in the motorcade. IMO, anyone the commies tried to kill is a hero.