That earlier quote is simply a distortion of the banners the kids carried during the demonstration which read something like "Why should we clean our rooms when you won't clean the planet!". A pretty valid point when you consider that adults are supposed to show a good example to children.
There is of course no doubt that an element of climate change is natural. However, to deny that humans are significantly contributing to that change is no longer questioned by any reputable organisation or knowledgeable group. I noticed recently that such groups are now refusing to engage with climate change deniers simply because giving them oxygen achieves nothing and distracts us from the main objective. I'm largely adopting the same attitude.