It seems like he feels the need to tell his allies when they make mistakes. But he is overestimating his understanding of the game and most times his assessment of the situation is wrong. There is a right way and a wrong way to discuss with someone if there were a better way for a certain spot to be played. In my opinion his way is not ok.
At the same time he seems completely blind to the mistakes he makes and if you try to discuss some of his mistakes, even in a manner way, the BM from him rises to a completely new level.
He has been very BM towards me as well. I have been insta banning him from my games as well, though I haven't played in the last 3 months. When I join others games, I tell the host that I dont want him in my team.
The reason we play the game is to have fun. Roia's toxic behaviour takes the fun out of the game. Everyone makes mistakes. That's how we learn. We make mistakes, we analize them, we play again and most importantly - enjoy the process (when roia is not around)