Her and Kan-E “bailing” on Raubahn was the best option. Them intervening could have been seen as an act of war (via assisting the alleged assassin of the queen and their alleged co-conspirato/actual murderer) and could have lead to the city states going to war against each other.

Which if that happened, or even if they’re was any form of discontentment due to them intervening at the banquet, Garlemald would jump on that shit like a fox in a chicken pen. We already know they have spies within Eorzea that they could use to destabilize the region.

Them leaving Raubahn was ultimately for the best because what would have happened if they tried to help him could have been much worse.

And in Merlwyb’s defense; she was ready to throw down but one of her guards jumped in front of her and was like “hey, let’s skedaddle” and I’m pretty sure the rest of them would have wrestled to the ground had she actually attempted to intervene.