I don’t think they’d ban you for leaving a key in the situation you’ve described.
Pretty sure as they say its
I’ll give an example. At the start of the season me and the boys went into 7s/8s/9s pretty quick.
Along the way I have to say almost everyone we met in Week 1/Week 2 met at that key level was both good and patient.
We had one tank though in one Dawnbreaker run. Very bad but also very angry. We had one wipe because he moonfire’d a mob in Narnia and then he leaves (20 minutes left…. btw and only 1 elite left before 2nd boss). I guess that kinda behaviour again and again would lead to disciplinary actions.