For some reason, there are Harecs, Shaes, Doldrens and Iunes who like nothing more than running around in this mission CQCing the enemy. Now, that's all well and good, but you see there's just one problem with that - they have exceptionally low health and go into wounded state very quickly.
But more importantly is the fact that they are the high DPS of the team and their (predominantly Shae, Harec and Doldren) job IS Antagonist killers and taking out the turret gunners. This way it leaves the canister carriers a path to not get taken out by them. This isn't just unique play to this mission but EVERY mission really. The alien faction are essentially Antagonist Hunters with all the necessary skills to take them out. The fact that Harec can take out enemies from one end of the map to the other, attaching himself high up on walls and structures and Shae has lock on ability, pretty much defines your role and where you should park yourself in the game - OUT OF HARM'S WAY!
If you are lucky enough to play this mission with one of the Alien faction WHO KNOWS WHAT THEIR JOB IS, then you'll breeze through this mission. Sure, they will moan about the fact that they need to kill grunts in order to build up their score. I accept that, completely, but if you take out the Antagonist, you've got 'x' amount of time to take out the turrets then grunts, making the game safe for your team. I've regularly got the highest score on this mission as Shae and Harec (never really played with Doldren and Iunes) with high 9 scores and over 10. It's about priority and remember it's ALWAYS about the team and your success. Antagonist -> Tank Turret Elites -> Grunts in that order.