The US missed the opportunity to take this guy down in 2004, when Sistani purposely looked the other way. Back then he was just another hoodlum with a crew. Now he has become a larger political force.
I agree with you, and I would note that since 2004, a series of Sistani’s lieutenants and employees have been assassinated.
IMO, Sadr is now well established, even in Najaf, where he used not to be. He is player - powerful and ruthless. It is a mistake to underestimate a man like Sadr.