Whitman's article is pretty much showcases what is so inconsistent about arguments for the liberal international order. I'm not an advocat against that order, I like the world I personally live in, but it's so easy to see the "selfish" goals of Britain through Whitman's attempt at defending a "rules-based" order. For example, see this passage which looks at the Integrated Review published by the British government:

The Integrated Review section on the Indo-Pacific tilt outlines a framework that stresses economic opportunity and the promotion of British interests in maintaining open societies and upholding international norms and values. It also outlines an ambition for a ‘persistent’ engagement by the British armed forces in building security capacity for the region.

At the same time as we maintain "open societies" with "norms and values," we beef up the military in the region. I'm not arguing against this, I'm just saying that the rhetoric used to defend it is ridiculous. "Rule-based" is not a liberal system, it's a hegemonic one, and Britain wants to keep their place as an influential country as they leave the EU and probably become less and less important on a global stage.