I haven't been in those team comms so I don't know how rude or toxic he was. But from watching esports I have always observed that East Asian and European coaches are the harshest and they bring out the best out of a team. Esports is a job after all and these people are striving to be the best. However, there needs to be balance to everything. You can't go overboard, specially with youngsters who look upto you and might take anything you say to the heart. Afterall, the same water that hardens the egg, softens the potato. As a veteran it's important to understand what works for whom.
I have seen sacy scold zekken for example. They were playing ranked, they were in a 2v1 and sacy didn't like zekken peeking so he let zekken know that instantly. zekken funnily said "look at the scoreboard, I am top fragging and look at you". Of course he was joking and they laughed it off. I don't think zekken is gonna be fazed by his toughness and I also don't think he is gonna be as rude in a different language to a place where they have different culture. But it's necessary for there to be a healthy work environment in esports specially with so many youngstars and such high pressure already.