To give some context:
The two alliances had been in talks for a couple of days by then, and both sides were instructed not to hit each other. For the most part this was followed, but as there were many NW and ghost cities to take, it was inevitable that players on both sides were targeting the same cities, in some cases accidentally breaking each others' sieges (reservations were not shared at the time).
Now Nex's case was different. He knowingly attacked Radlick's siege with a griff nuke, which was fended off. According to Radlick, the two spoke about the siege, so Nex clearly knew there was a CS there. After the griff nuke failed to break, Nex followed it with another LS nuke, killing the CS. The correspondence he posted happened after all of this. As he showed that he clearly did not care for making peace with his teammate, he was kicked. We do not need such a player in our alliance, but if This Is a Mistake believes they do, then I wish them the best of luck.