Once on a demilitarized zone at portals, you do not get the neutrality advantage. To get it back, you must either destroy the enemy that is attacking you so that after about 5-10 seconds you regain neutrality or jump the current portal you are at. Also be aware that there are portals that do not have a demilitarized zone. All battle maps do not have this protection except 4-5 when aliens is attacking you or jumping to pirates when attacked by either players or aliens. However, when you first directly enter an enemy map, you will temporarily gain neutrality, but that neutrality will be lost after a few seconds.