My suggestion is, when the fronteersmen arrive on station, it is already too late for its' native population. The Kharaa have eliminated all resistance, and now have the opportunity to expand the infection to the entire structure. Aiding this task is the corpses scattered throughout the facility. It still holds servicable envirosuits which the Fronteersmen can commandeer.
Branch 1) Corpses must be dragged back to a res tower--they give res
Branch 2) Corpses must be touched by infection (dragged to it early on)--they speed up infection
Branch 3) Corpses must be "used" by a Gorge--they give res
Branch 4) Skulks or Lerks must bitegun corpses--they give res
For the Fronteersmen, the envirosuits on offer provide a way to cross hazardous areas before the advent of jetpacks, since wading through environmental hazards to reach the contested res tower or siege vector requires either speed or protection to minimize exposure. When the Kharaa reach it, (via their' speed), no doubt they will be damaged, making these areas easier to hold. These suits are ablative, but also reduce damage from spit, acid rockets, and gas, and render healspray harmless. Marines wearing these suits are a great danger to undefended Gorges.
Thank you for reading!
-Edit- These are early game, they don't respawn