You can't kill anyone before RG. RG need to be your first target (unless you can 1 shot your first target choice). That's why he is so good. QGJ's special ability is useless against him, because even if you remove the taunt, RG will pop it again, when you hit once more your previous target. It's situational though and depends on the % remaining health of your 1st target choice. RG is not in squad to deal dmg. He is there to give time to the other allies and to absorb the burst of the opponent. In most battles he dies but the allies can do their jobs. Plus if he has a chance to use his basic stun, thats a huge advantage.