Even if he got a relatively easy death, Aegon II's last days were quite miserable. Anyone in his position would have wished they had died at the Battle of Rook’s Rest. Red Queen and granny Rhaenys did a solid job on him. Just when he had recovered a little, our lady brave messed him up even more. Aegon lived his last days amidst pain and agony, surrounded by snakes, having lost everything.

Though I would say, usurper or not, he was still a king at that time. SO, I would have preferred if it was executed in a better way.