A lot of the kill challenges have written requirements which don't match up with the actual effective requirements. A good example would be the Inflate-o Ray and Disintegrator challenges: killing Cops and Military with the Inflate-O Ray counts towards the kill challenge, but killing them with the Disintegrator does not, and only triggers when you kill Zin. The description for both challenges indicates you're only supposed to kill Zin.
For what it's worth, I'd like to see most of the challenges allow killing Cops, Military, and other sim-humans for the challenge. End game your only shot at taking on Zin is to cause some chaos, and when they do show up they're composed mostly of Marauders, Murderbots, or ships, and quite a few challenges just don't work for those enemies (you cannot Inflate-o Ray anything except actual Zin, for example).
For what it's worth, I'd like to see most of the challenges allow killing Cops, Military, and other sim-humans for the challenge. End game your only shot at taking on Zin is to cause some chaos, and when they do show up they're composed mostly of Marauders, Murderbots, or ships, and quite a few challenges just don't work for those enemies (you cannot Inflate-o Ray anything except actual Zin, for example).