Was certainly rude.
Rude isn't just a emotion (one can accidently do it, hence the attempts to apologize), it's a circumstance that causes friction.
Take her self righteous attitude with O'Brien, which O'Brien was completely and reasonably justified to have- even the Cardassians would think it rational enough for a war veteran who faced off against them, and move her circumstantially away from O'Brien and the enterprise, and set her.... hmmmm.... on DS9 right after Garak informs Sisko he was intact behind the assassination of the Romulan, just as Dianna was walking by..... shocked as hell at the very unFederation emotions coming from the Captain, barging in cause it's "her job", catching enough of the conversation that she realizes she just stumbled in on some galactic high crimes.... and gives a twisted face look half horrified, half paniced that says " I'm Telling".
Man.... 30 minutes later Sisko be walking in front of Quarks with Odo, and you'll see Troi's stupid frozen head smack into the window from the outside, floating in space, with Sisko staring in disbelief and Garak walking out of his shop while people are screaming, holding cloth and thread, looking up.
That's what happens to rude people like Troi who don't get that butting in, under ever more tense escalating circumstance, can go very very wrong.
As far as I know, Picard never faked a cause of war, but Picard and his crew as the flagship was in a variety of nearly as bad circumstance. Wars happen, emotions happen, she needs to have a healthy respect for hatred and disgust, even homicidal rage at times, cause soldiers do kill from time to time, and being a pure stoic or angered inspired when your told to fire doesn't matter- you fire, if need be kill, hopefully the enemy dies. Perfectly reasonable for hatred, disgust, mistrust to take root- that's emperical data inspiring that, personal experience.... "These people are tricky". I think the Cardassians would take it as a compliment, a acute observation had they known for certain.
It is only a issue if it effects the pragmatic work ethic and professionalism O'Brien has to project. It didn't, do she best keep her opinions to herself. What is he gonna say if she demanded a meeting? That he hates them, doesn't give a crap about her opinion, cause that's stems from his experiences, his dead comrades, from Cardassians being unapologetic about it all. He is perfectly right to say rank aside, she can shove her breathing exercises up her butt, he is perfectly healthy considering standard expectations for someone of his experiences, and Starfleet is okay having him around, has intact thousands just like him, hating the Cardassians, yet doing their job. Doubt he wants to waste his time talking, needs to go fix things.