Indeed, something had to be done, does that means they jump to high treason.  No, I sense Lannister machinations here, throwing the whole realm into chaos.

Dont forget to add in the Starks and the Arryns, who are also traitors against the Targaryans.

This is the price you pay for betrayal.  The Starks took up arms against their rightfully anointed King.  The King being insane is not reason to betray him.