The UK Government is inviting him to the UK and most Brits are in favour of it vs those who are not. Why do you care more about what the noisy minority and the opposition believes? We could judge the US by exactly the same standards because your country is also riddled with noisy leftists despite its government.
Are you the scotsman back under a different name, lol? What’s good for the goose is good for the gander. Don’t defend your country’s complete meltdown over Trump. Be embarrassed about it!
Look, when China rolled out a red carpet for every leader in the world except Obama, who they made crawl out of the back of his plane next to the guys carrying groceries that was a deliberate snub. And nations like the Philippines who are looking at whether to stick with traditional but of late undependable ally the USA or align with China see that as a show of how weak the USA really is and how bold and strong China is. The optics matter on a global level. When the UK invites Trump then sends him to a lesser venue to speak, then (potentially) cancels his speech there are those who will see this for what it is: a government with a weak and uncertain relationship with the USA. Good luck negotiating with Brussels with those optics playing out.