In short, we aren’t on track to an apocalyptic extinction, and the new head is concerned that rhetoric that we are is making people apathetic and paralyzes them from making beneficial actions.
He makes it clear too that this doesn’t mean things are perfectly fine. The world is becoming and will be more dangerous with respect to climate. We’re going to still have serious problems to deal with. The problems just aren’t insurmountable and extinction level.
Didn’t you answer your own question? You can advocate, you can organize, you can lobby. By pretending these things don’t give you power, you strip away your own power.
The point is to sway the government’s actions through public opinion. One can argue how effective these tactics are, but doing absolutely nothing will surely accomplish absolutely nothing.