>"Yeah I am really unperturbed" doesn't make sense in context of it's parent

It's not just unpertrubed, it's also "not impressed".

In the context of the comment it basically means "I see this speaker announcement as nothing special, what's the big deal?".

The commenter specifically used the word nonplussed in reference to the ranking of this post on the front page. The fact that their surprise and confusion stems from the promotion of unimpressive stories does not change the meaning from surprised and confused to unimpressed.