Again, the complaints are not that he got traded, or that Drury told him he would go on waivers if he didn't accept a trade. The complaints were around Drury & his (lack of) communication. Allegedly, Drury never bothered to speak with him in person or on the phone for ~5 months. The GM never spoke with his team's captain or had the decency to even tell him that they were going to move on from him.
Whether or not you think that's a valid complaint is a separate thing. I'm also not saying Trouba is not devoid of blame himself. He played really, really poorly. I'm glad we've moved on from him. But Drury's method of doing business and moving on from players and personnel, not speaking with people or treating them like respected members of the org, THAT is what is rubbing people the wrong way.