Alternatively it could be that people absolutely disagree with your concept that "if crime causes the police too much hassle then the police shouldn't deal with it", maybe because they were brought up to believe that people who do wrong should be punished when caught, which apparently is an odd concept nowadays in our infinite grey world, I mean appeasement of criminal activity has never gone wrong ever has it!
Oh and the Golden Rule wouldn't count here as a conviction of those XR folks wouldn't be classed as against general public policy (i.e. public support) as only a minority support them or a silly upholding of a law - which is the most common use for it currently i.e. stopping Ye Olde Laws from causing issues today.
Anyway, the actual result of our grey world is that thousands of people feel perfectly entitled to disrupt London, including causing criminal damage, knowing they'll be able to walk away scot-free all because "it's too much hassle and we can just clean it up tomorrow" - and people wonder why so many kids today have no respect for law and order