From what I read it seemed he was just expressing his opinions. He might have been a little assertive, but not necessarily disrespectful. When people have played this game long enough and try to help others you generally see two different approaches. You either dictate what you personally believe is the optimal choice for the individual or you explain all the options and possibly outcomes for each one, possibly followed up with your opinion depending on the situation. I usually try the latter, allowing the individual to make a choice and play the game their way otherwise I feel as if I'm playing it for them. However I would be lying if I said I haven't used the first method from time to time, especially when it's time critical and the most likely optimal choice. The first method doesn't have to be considered disrespectful.
Regardless of all of this, I feel as if Nexon is in the wrong, and it's quite obviously when reading the the comments on the thread that im referring to which was closed. There are so many instances where it seems like it's constant 'damage control' with the forum moderators. Cessa brought up some things that have been posted that are clearly against the ToS and haven't been delt with properly. I see them on a regular basis. Also, I find it funny that the moderators always bring up "this thread is off topic" mostly when they intervene for damage control where in fact nearly all threads become off topic sadly.
TL;DR
A moderator called out a user that was criticizing the game and standing up for their self after other users where being belligerent while backing up their different personal opinions and perspectives. It ended in the user being banned while trying defend their self...