I agree, that's a really great example. It would be even more natural for tags in org-mode, which already supports drawing tags away from the text itself to a far-right column, but they really could be moved in the other direction to the left of a hairline next to the bullets, and they'd be more readable.
BTW, Nicolas has a lot of interesting packages exploring use of graphical design elements in Emacs apart from the Nano Emacs stuff; for example, there's https://github.com/rougier/svg-tag-mode. I love how he chooses to represent dates and dates with times attached, and to distinguish active vs. inactive dates with shading rather than "[" and "<". That actually makes it easier to spot a common org-mode mistake without having to call up the agenda.
I love the exploratory screenshot of a function reformatted with the comments floating on the left of a hairline instead of next to the source, with the function name nice and big and bold right next to the version control info.