You may have done it after I changed it, but just in case....
*EDIT* - Defeat Nictus Romulus Augustus in the Imperious Task / Strike Force.
Taz, my crab spider just hit 35 last night and has only run the TF once, but he has the badge (I just checked). I didn't notice when it rewarded for him, but when I got it on Catharctic, it awarded as soon as Nictus Romulus went down the first time. Yes, that was after I had done the TF with him already, but maybe that was just a heroside glitch. Orange Jo Jo (Dominator) got it when he logged in after the badge was patched into the game. He had done it twice, though. So...yeah...the objectives are a bit fuzzy.
Solution: Everyone do it a second time if it doesn't reward the first time!