So, he was on scene himself. So what? Still enough reason to withdraw all ambassadors from his territory or something. Laying that trap was outrageous.
Also that "good" guy in the end would have pissed me off without end. I'd be all, "I'm summoned here by YOUR Emperor, against my will by the way. I'm not here to let myself be belittered by somebody, who better should listen to what his Emperor ordered him to do and NOT act against it on his own accord, I'm sure."