Because there is no point using AP at all in secure areas.
AP, with health, damage output, etc... are ways to balance combats.
Unless you are very hated by the people you share rooms with, you will have no need to fight or even be competitive in platoons, so things like carry weight or action points just get in the way for no reason.
You can have AP removed for platoon by default, or make that a late support perk. The point is to get efficiency in lone boring activities, so you can spend more time enjoying the actual game in the city.