Is that a threat?
likely refers to the "Military Police Corps" (or just "Military Police") as mentioned in Yellowjackets Season 2, Episode 5 ("Two Truths and a Lie").
If you meant something else by "MPC" (e.g., a music production software or another acronym), please clarify, and I'll adjust the response accordingly.
JESSICA (50s, cynical) opens the door. A MAN (40s, buzz cut, rigid posture) stands there. He holds a folder.