He was going to die anyway. His case was on appeal. But Iran had him hanged prematurely and made sure everyone knew about it. People do things for a reason and regimes that are sufficiently eschatlogical-utopian are internally coherent as to strategy, since they are all a bunch of extremist lunes.
So what was the strategy and what does it mean?
Essentially it means that Iran was involved in 9/11 also. Or at least it ought to be taken as meaning that. It means that Iran was a co-conspirator with Saddam. Other evidence has emerged linking both Iraq and Iran to 9/11. As well in all likelihood at least one faction of the Saudi regime. But the murder of Saddam by Iran is just another matter which singles them out.
Saddam had denied any involvement in 9/11 right up to his death sentence being approved. But he knew all that time that he had a right to appeal. So did Iran. And it looks like they weren’t about to take the chance that he might try to cheat death by cutting a deal with the Americans.