In the same vein, the US also taxes foreign income that has no real nexus in the US, so if that’s fine I fail to see how they can’t tax a citizen’s foreign assets.
On that point I’ll have to grudgingly agree with what I assume is the conservative position. I see no moral or legal basis for a county to tax activities that take place outside their jurisdiction. The citizenship of the people involved shouldn’t change that, but according to the US (and, as far as I know, no other county), it does. I generally see any conservative legal victory as a setback, but if this case some stops the practice of taxing US citizens living abroad, I’ll consider it a silver lining.