OK MilPilot.
I give it a try.
Your question is asked frequently in fleet forums, for the reason boxjockey stated. Some CX pilots want bases and CX has to put vacancies out for bid and can only hire DEFO's for unfilled vacancies.
However the answer which came up in the fleet forum I attended in regards of NA bases is, that at the moment there are a lot of outstanding issues caused by onshoring and other reasons. No time line was mentioned for opening more slots on Basings or new bases. Your guess is as good as mine when there will be more base slots. However having said that, I believe the last Basings bid had 4 Capt and 2 FO vacancies in NA. So, there where some bases available.
If you are in the pool, call recruitment they might be able to give you a better answer.