You can afford to place them on base sectors just like any other faction.
Multiple streamers prove you wrong on this every day in multiple games, its not even worth arguing.
Also, focus on emplacements being rather important part of progression and an option that should be valid is quite faction specific as well.
Brace IS a retreat equivalent for emplacements, no matter how you try to twist it.
The new cooldown and current modifiers from explosives and flames means emplacement will be hardcountered and destroyed 60 seconds after they have been spotted(force brace, kill it 30 sec later with barrage weapon of your choice).
It would be a retreat equivalent if retreat was a "your squad is immobilized but cant attack for 30 sec, but they tank like jesus himelf, waiting for support, and they can brace again if no reinforce showed up in 30 sec"
Retreating a squad = the time they go back to base, return from the base, heal / reinforce ( they can die retreat) is kinda long