You killed them inside the CZ? If they were CZ newbs, then I'd assume that was simply shock about being killed so fast.
From my own, meagre experience with CZs: when I decided to try a CZ, I went there in open with the intention of supporting both sides, i.e. do one round for the Feds, then one round for the Imps. I was hailed while SC'ing to the CZ by (I think) an Imp CMDR, inquiring which side I'd support. I became very nevous and in a short chat, I was able to convince him(?) that I was only there to watch. I guess that, had he attacked and killed me inside the CZ, my reaction at first might have been on the same lines as you described. If I had a short time to think it over, though, I would have had to admit that I'd have given my best trying to kill you - 'vettes give the biggest bonus

.
Would I have logged in a CZ? At that time, possibly, if I had thought of the option. Now, with a bit more experience - unlikely. If I don't want PvP, I go into solo or a PvE group. heir connection, whichever means)
As for reporting combat loggers - there are supposedly reddit sites for that, although from the receiving end, it may be very hard to determine whether they logged illegally (i.e. killing their connection by whichever means), legally (through the in-game menu - had to do that yesterday in CQC, due to a RL NMI) or through a server disconnect (hapened to me yesterday in CQC, twice - after the second time, I didn't log in any more).
- - - - - Additional Content Posted / Auto Merge - - - - -
You'd have to ask CMDR Mobius for the exact reasoning there. My guess is that, when setting up the group, they had to draw the line somewhere and decided to put it there. Including piracy would have made it very difficult,
in case of an accident, to arbitrate. Originally, Mobius was/is an open (as opposed to deicated groups like FGE) explorer group - piracy simply had/has no noticeable significance there.