Never heard of this batch file, but I wouldn't trust it with online play. I'm not a big hacker though so I dunno how these things work.
There are ways of ensuring you don't lose them when playing online with randoms:
1) If everyone leaves and you're the host, you'll get left to play solo on your own, then you can close the game by pressing Alt+F4 to kill the process. If you're not the host, and the host leaves, you'll get disconnected anyway cause BO3 servers are crap like that. If on the off chance that the host migration works and then you become the host, see the first sentence. I don't know what happens if, say, there is one other player, you're the host, you go down and then he leaves, so keep option two in mind.
2) Keep a Self Medication on. All the while you have Self Medication on, the game can't end unless you allow yourself to bleed out. So if everyone goes down, then you go down with your Self Med, rather than the game ending, you go into last stand and have a chance to revive yourself by killing a zombie while you're down. So the only other ways the game can end is either losing connection to the host if they quit, or if you're the host you'll get left to play solo, in which case you can Alt+F4 to close the game or disconnect.
3) Worst case scenario, you don't have a Self Med, everyone has gone down and it looks like you're about to go down as well. GET OUT OF THE GAME as quick as you can before you die! Press Alt+F4, rip your internet cable out, whatever, just do it. If you see the Game Over screen, gums lost.
Enjoy