In all honesty, I'd tried to kill the Jarl instead, as a lesson to whoever dare to cross the Dragonborn.

Sadly, he is invencible, just like his son and many other NPCs. I know they did it to not break the main quest, which is a pity.

Lots of high profile, annoying NPCs are protected by plot armor. I wish the Radiant AI could deal with this better. Playing nice or playing naughty, you end up being treated the same in Skyrim.

At least the mods allow for a quick, if empty, retribution.