“I would guess that it has something to do with the ten thousand zombies outside and she doesn’t want to make any more noise than necessary.”
That’s a good point but everyone else in the episode is making lots of noise, and Tara, Rosita, and Eugene are talking right in front of Z’s looking in the freaking garage window.
Ever hear a 9mm shot up close and personal? Your ears ring for hours. Waaaaay louder than even ten people shouting.