You clearly think you've spotted something that everyone else is too thick to realise, so you'll have to spell it out to us.
It appears that the family has three children, but we don't know that to be a fact, one could be a friend who's come for tea.
I would hope that if Quorn is marketing based on the fact that it is lower carbon footprint than meat, they have some reliable figures to back that up.
So what's so wrong about their suggestion about 'taking a step in the right direction'?
After all, the solution to climate change is never going to be everyone doing things perfectly, because they simply won't.
So the next best thing is as many people as possible doing the best they can, ie making a few small sustainable swaps that they can live with, rather than a few people doing everything absolutely right and most people doing little or nothing, because it seems too difficult or unpleasant to even try.