Sam I agree in part but actually the west is not the source of all good things, Russia for example had the Russian revolution which was a kick up the backside to the complacent conservative west in much the same ways the French one was . Russia has also contributed greatly to the arts and sciences. China developed the Confucian ideals and has made contributions certainly to the arts but in an eastern and not western style and perhaps that's rated less important than say Shakespeare or Rembrandt. Equally i don't think you can use the excuse that enslaving people ,stealing their land and territory was any less evil 200 years ago than it is now.
But the other points you make about a sort of generically liberal Democratic idea in the West (which we are just bout clinging onto) are legitimate and good reasons why China should be challenged , whether they care or not is another matter. ,
And the point I was making was that its hard to be holier than thou if you are the Uk Government when speaking of HK.