@Lucius Cypher But wouldn't that mean that if Eos gave Marquis command, Eos could easily create and grant Marquis shutdown codes in like, a nano-second? Eos is Eos.
If Eos gave him those commands, sure. What I'm uncertain of is if Marquis received those commands from Eos or not. If he had retroactively received them, then fine. But otherwise it seems like he just created a code to interfere with a frequency that really, only those linked to Krieg would normally have access to. The only common channel that the Killa Kan shares with the Machina army is general communications, which most wouldn't have any use staying on since they lack the ability to speak or otherwise communicate.
Basically, the Killa Kans have a fairly simply programming, which is a double edge sword. On the plus side, they won't do anything they aren't programmed to do, but what they're programmed to do is very limited. They can follow, they can attack, and they can blow up. They cannot do anything that doesn't involve one of those three commands, but they can do other things within reason of those commands. They can attack a location with no enemies, so they're effectively waiting until enemies are there. They can follow someone even if there are enemies near by, so they won't attack until the person they're following is attacking or tells them to attack. And then they can just blow up for whatever reason, usually because they're too damaged to actually do any meaningful fighting. They won't do construction work, they won't really do any specific bodyguard duties beyond killing things, and they don't really complete objectives unless it involves killing something.