That's a hell of a point!
Frankly, I don't have any answers that aren't strained.
The writers of these zombies shows really let the viewer down, in my opinion. Sometimes we see a lot of plot induced stupidity - just stuff that makes no sense and is designed to move the plot along.
We saw people arriving as refugees so they clearly are taking people in. But then we are told they are shooting people or not letting people go into the infected zone (I assume that means areas over run with zombies).
So I am confused. Did the person want to be rescued? But if they are hiding from the military they would not signal into a military base. Is it unsafe for them to be on the street? If so the mom went out on recon and found dead bodies, guns on the ground and no zombies.
I think she hinted at the fact the military is killing non zombie humans. Thinning the heard? Again, if that is true, why signal into the base of the guys going to kill you?
Also, we assume the military killed the person sending the light flashes. It could have been looters.
Or the person sending the light flashes might have won the fire fight, against soldiers or looters.
Pretty darn coinky-dinkle coming right after Travis reported it to the CO (who I think is playing dumber than he is).
Looters don’t signal other humans who aren’t looters.