I didn’t do any messing around testing options or changing settings. In Safari, Menu: File/Print, picked “Save PDF to DEVONthink 3” and worked just fine.
The same outcome with Safari and it’s “Share to DT3”.
However, the original is full of JavaScript that is loaded from all over the net. As I already said elsewhere: If you want to capture HTML pages for archiving, you’re better off with PDF.