I must not be very smart. Why is he still alive?
Because Hillary wants him to run with her as Vice President.
He telegraphs his every move and is incapable of undertaking anything with secrecy or discretion.
The most radical Shi'ites follow him and as a result their movements are highly visible and easily monitored.
His slavishness to Persian foreigners and belligerent insistence on his own importance offends and alienates the majority of Shi'ites who look to the pro-democracy, government-aligned Ayatollah Al-Sistani as a relgious leader and who distrust foreign, Iranian influence on Shi'ite institutions.
If Sadr were killed, he would likely be replaced by a smarter, more discreet warlord who would be able to build broader alliances for the radical agenda among Iraqi Shi'ites.