It's left open to interpretation. Remember what Lebedev (Or maybe Beanpolev, can't remember) tells you right at the beginning of the game? You managed to survive two emissions, but the strain it put on your body was so intense that another emission would kill you. Or something along those lines. Any of the regular emissions kill you, so he may not have been too far off. That anyone survived the last emission shows that it wasn't a regular one, though, and CS was wrong about every other theory they had, so Scar might have survived and been brainwashed like the others. He might have been better off than anyone else, because of his natural emission resistance. Or, he could have died while some of the others survived.
Some other members of CS survived, but we don't know if they were involved in the attack on CNPP.