It is probably a programming nightmare, but now that they are with Sony, they can hire enough staff to make quality of life improvements like this. To avoid exploits, when equipment locks, the server should record which players and characters are in the fireteam as well as the full loadouts. If a player disconnects, when they try to rejoin, the server verifies the player and character loadout. If it doesn't match, the player can't rejoin. If it matches, they can rejoin with no special or heavy ammo and their abilities are drained (avoids the ability to cheese by forcing a disconnect; plus, I'm assuming it would be to taxing for the server to continuously update ammo and ability status). Is this punishing...yes, a bit. But, not as much as not being able to rejoin.