You talked about their teams, like "jame being stuck on t3 teams" instead of talking about the raw skill of the awper. And apart from el1an, all of those he mentioned are actually pretty good awpers. When ZyWoo first appeared, people also thought he was a fluke. Now he's been Top 1 for two years in a row.
You don't need to respond nicely to someone who sperged the fuck out in his initial response, but I guess calling someone a retard says more than calling someone a clown. You don't need to go too far.
And if you keep cordiality, even if you don't respect the person, your point will get across and theirs might get unseen.
Anyway, have a nice day.