Believe it or not, That's exactly what he was trying to do. Some people consider it a viable strategy to be a complete asshole in order to tilt the opponent. Their aim is to distract you and sabotage your momentum, If you can't keep your head in the game and ignore the rants then do as people suggested and join your own party. Unfortunately there is no other way around it since NRS don't give a damn about kombating toxicity, That's the one thing i'd give to Blizzard. You get suspended for as much calling someone a bad player in their games.
I tend to agree although I feel like it is a bit of a "dark art" I think shit talk and taunting is a good way to tilt your opponent and I don't really see anything wrong with it as long as its not personal about your opponent.
I'm sure a lot of people will tend to say its a bad thing to do or "bad sportsmanship". But it exists in almost any competitive arena be its sports or otherwise and is respected.
If your playing KL lets be honest you want to win. So whether you're a casual player or not you will be doing what you can to win.
I have trash talked a little online during sets but it's never personal it is always about the game and more specifically the match.
A lot of times I'll call someone out for D1 mashing or if they are grabbing a lot or basically doing anything predictable I'll start saying "here he goes he's gonna jump 3 into grab or here comes the raw Fatl blow ." The whole point is I don't want to deal with those tactics and when you start making certain players feel like your critical of their tactics in the course of the match and you are predicting their moves they want to prove you wrong and they get off their game plan. Even if they are winning with those tactics their ego gets involved and they want to show you they are capable of more.
Other times if I win a match during a set and someone backs up and goes to character select I'll chime in with "okay hurry up and pick Scorpion so you can Yolo teleport your way through the next match. "
SO in that way I feel trash talking is incredibly viable as long as its not disrespectful personally or vulgar.