So got banned for "ninja" in a dungeon.

I was playing today on lorderon with my rogue and doing dire maul with RDF and a sword dropped from the trash:

https://wotlk.evowow.com/?item=2244

As soon as i saw it and looked at the stats and the look i rolled need. So did the tank paladin. I won the roll. As soon as i did he claimed ninja because it had strength on it. He said he was going to report me for ninja. I honestly didn't think much of it and after a big rage in chat he left. Few hours later while playing i get booted from the game and i realized i got banned for ninja.

I am making this topic to request help and try to make sense of what happened. How is it that a paladin calls me a ninja while he rolled on a dps sword while tanking and reports me and gets me banned for what is clearly an item "he" tried to ninja. An item that is not supposed to be for tanking .Tanks are supposed to use fast weapons not 2.8 speed weapons.

Am i in the wrong? Or did he just abuse the report system. He got mad and lied to the GM and got me banned on a false claim. If he is wrong shouldn't he be the one to get banned.

Please can someone give me some answer.

Thank you.