I think you will find that this is more to do with British Internal politics rather than Foreign Affairs. This is all about Brexit and the latest move by those who never accepted the decision of the British people and who still look to overturn it. If the clause had been accepted, it would have been virtually impossible for the British Government to sign trade deals with any other large country.
Come on. You can't have it both ways. What
@Petrolicious88 said it's true. It's going to be difficult to prove genocide has taken place. (The very ideal it is happening is ludicrous. Now this is definitely for internal politics).
With regards to Johnson. Yes he's definitely playing politics and try to have cake and eat it. Where's the Britain is great? Britain can do deal with anyone? Etc from the rhetoric of the Brexit fiasco? All the sudden, Britain haven't got the balls to go through with their own belief.
If Britain is genuinely concerned about 'genocide' in China! Genuinely concern about human rights abuses. Then it should start with what happened in US with George Floyd and the runner gunned down by father and son or the black man shot in the back by cops as he was running away.
It should also stop making 'blood' money from the Saudis. And it should definitely call China out on Xinjian.
But alas, no! So you're right, it is pure BS for internal consumption. Johnson is being shown up again what a charlatan he is.