I think if Trump sides with Putin, the UK and Europe are completely defenceless because they rely on a US underwritten NATO for defence. The UK is broke and has no real way or protecting itself from anyone - this makes it a soft and easy target.
You are all bagging Starmer for walking a delicate line. But you will be up shit creek without a paddle if he crosses Trump. The UK needs the US more than the US needs the UK.
This isn't WWII, there are no strong allies at your back. The UK is no longer a world power, it is now a minnow in a sea of sharks. Things change.
Trump wants Greenland for the same reason he wanted Venezuala, controlling oil supplies and movements between China, Russia, and the Middle East.
He might be mad, he might be bad, but pretending that he is stupid or demented is a mistake.
It doesn't matter why the UK is soft. Other countries are getting hard.
Or who knows maybe it is all headed off. Israel takes Palestine, Russia takes Ukraine, US takes Venezuala (and maybe Greenland), and China takes Taiwan. And the big boys all rumble a bit, but ultimately shake hands, make the awful deals and we in our rich, soft countries get to sleep relatively safely in our beds.
There have been worse outcomes.