So @Buggs_LeRoach pointed out something I overlooked in that blog post: if you interfere in a limited engagement, you get CONCORDed. This is an ALTERNATIVE condition to what was described above.
@Labadina to put that into perspective (from https://support.eveonline.com/hc/en-us/articles/203268611-Duels-Limited-Engagements):
Limited Engagements are created on attacks towards other pilots that are under a suspect or criminal flag to allow them to defend themselves but can also be gained from accepting a Duel Request.
Since ship3 was a suspect/criminal, a limited engagement formed between him and ship2 - hence interfering would be a CONCORDable offense.
So now that we know that you will, in fact, be CONCORDed during limited engagements per that blog post, we can safely conclude one of two things happened:
- Ship1 had his safety on red, so he was able to rep ship2 during the limited engagement, and this led him to being CONCORDed
- Ship1 had his safety on green/yellow, so he should NOT have been able to rep ship2, but due to a bug he was able to and he got CONCORDed - this would have to be reported as a bug and a reimbursement request would need to be filed.
This is unlikely a bug, so he probably had his safety on red, which is Hisec is almost always bad idea unless you’re trying to suicide gank someone (if you’re logi, you’re not exactly trying to suicide gank anyone).