I find it very strange that the Swartalves beat Thomas so badly, they made it impossible for an Emissary or anyone else to question him, and effectively dealt a death sentence before the Emissary could judge him. The Swartalves are stickers for the rules, and their conduct appears to abrogate them.
This pushes me towards the Evanna theory, she wanted Thomas to abuse guest right and suffer death by Etri. This would require her to be Nemfected and upset with Thomas e.g . Seeking Asylum for Justine with the Swartalves. The way to infect a Swartalf something of Beauty, perhaps the headband.
Convenient that the GateKeeper isn’t present,