It's the hypocrisy of them, if you want zero carbon emissions by 2025, going to McDonalds after protesting is not a way to achieve it - you bring locally sourced organic food with you from home. But as you say, I've not seen much enlightened philosophy from the protestors. I saw a clip of Katie Hopkins arguing with a protestor last night, and there was nary a brain cell on show.
All I can see id a bourgeoisie rabble with unrealistic goals disrupting people's lives because they can, without sustained media pressure on them or criticism of the disruption to people's lives. Outlets like the BBC are rather indulging their hubris and ego.