Don't the Asur have methods to be able to figure out if someone is lying or not during trial? I vaguely recall something about the Everqueen having a truth sense, though if she's the only one with it then it might explain why such a method wasn't used when Dorial was, presumably, asked to give testimony, in case our trial wasn't important enough to warrant the Everqueen's direct attention.
Still, court verdict from the king and Asuryan's representative that Dorial has no criminal responsibility. For some people nothing will be enough and they'll continue to blame Dorial no matter what the Phoenix King says, but for the rest, in Dorial's case the tables are reversed: While there's a court verdict explicitly determining that we are guilty, there's a court verdict explicitly determining that Dorial is not.
The point is not that they think Dorial is lying, they think he is a failure of a swordsmaster who did not notice the that the person he has been assigned to got a bunch of elves killed. You do not have to think someone is criminally liable to dislike them.