Appeasement never works.
I also question the wisdom of quickly executing the rebels. It is much wiser to slowly extract every last bit of intelligence from them. Who are their allies? Who are their Imams?
Only after you know every thing there is to know about who these men are how they came to do this deed and you have their allies in your hands can you kill them.
They were probably afraid if they didn’t execute them quickly, there would be either new attacks to free them, or political pressure not to execute them.