Well normally casual is not an insult^^
I don't think it was ever used to Insult me either (so never?)

The Tank was obviously baddly mannered from what i read in your post,
but may I ask what your playstyle is that set him off so much and what he wanted you to do? (don't misunderstand me i assume it is something trivial and i know that some Players are simply mean for the most unnessecary reason but i already got some Players with "unique" playstyles and was just wondering (worst was the Blm who rp'ed as lightning mage....)