If we discuss what e.g. Java does better than Go and vice versa for purely technical interest, there is little emotional pressure. But if I feel that somebody is trying to make me use Java (or Rust, or C++, or Visual Basic) over whatever I prefer and feel comfortable with, I get defensive. When people get defensive, they become unwilling to admit shortcoming in their preferred language/framework/OS/..., and so the debate devolves into "You're wrong! - No, you're wrong!" and namecalling.
A person may have the best of intentions, but they need to realize that their words can have unintended consequences. There are places times and ways to properly discuss go's shortcomings, but there are also times when it is wildly inappropriate.
This is a good event for a very hardworking and capable part of oyr community. They deserve a little respect.