They agreed to play the role of Blood Elven spies and completely went back on it.
Void Elven operatives are vigilant, and will make sure the meeting is dispersed if attacked by a larger force.
TL:DR version: We were roleplaying in a way that could have been resolved both easily and IC, not griefing.
The Myrmidons arrived as a group intending on infiltrating the meeting - this means, like any good clandestine operation, they brought people along as backup in case things got bloody. That’s the reason my character was there, and this was handled IC.
We arrived at the gate guard where there were plenty of IC actions that could have been taken and would have been perfectly fine results for all parties - sounding an alarm, attempting to fight off the group, fleeing - which were not taken. Instead, there was an hour of an awkward blue-flagged standoff interspersed with rude OOC comments in /say.
There were lots of ways that OOC coordination could have been used to make the IC experience closer to what was intended - setting up a crossRP relay channel or Discord lobby, asking about expected numbers, expectations of combat (and how to resolve it, via emotes, duels or restricted RP-PvP), having a PC or NPC character as a relay to guide characters toward the meeting as examples - but none of this was done. What was the intended action should the infiltrators be spotted, or if those spies wished to take down one of the ringleaders? This was not established beforehand, and would have run into the exact same awkward silences that happened with us.
I worked extensively with Alliance counterparts across three separate RP-PvP campaigns run by three different people - I, and most of the guilds in our circle, are extremely familiar with this process and are willing to either make IC compromises to make the session fun for all concerned or not attend if our goals are in conflict.
There were also IC mistakes, such as having the meeting be easy to follow for Horde agents without any sense of vetting or relay for the safety of the characters involved, which contributed to this, but this can be explained by characters making poor decisions and is part of IC action and consequence. Part of the consequence of involving characters at war with Void Elves (particularly Blood Elves, who have a strong personal reason to want ‘the traitors’ to be ‘dealt with’) is that combat is a strong possibility.
The trouble does not come from this kind of event per se - it comes from the rude comments we received both in /say at the time and now with our guilds being branded as griefing for taking actions our characters would take and not having the communication necessary to allow us to compromise on those actions.