I'm kinda on the fence about contrib.admin bundling/using jQuery, but not for any of the reasons in this article. For me it comes down entirely to compatibility.
At my day job I work with the oldest Django codebase in the world, and also one of the largest. We do pretty much everything it's possible to do with Django, including some fairly heavy custom admin stuff. Quite a bit of that involves JavaScript.
At the moment, we have code actively using the current bundled admin JS, two different public JS frameworks and one private internal JS framework. This is the result of years of dev work making use of whatever tools we happened to be using at the moment, and all of it still works today; we even have areas where multiple JS frameworks are in use side-by-side on the same page along with reuse of the standard admin JS.
I simply don't know what happens to all that code if suddenly the admin is jQuery. I don't know off the top of my head all the possible intersections of libraries and frameworks and how much code would need to be rewritten as a result. And I really don't want to think about whether people who use, say, MooTools for their own customizations would suddenly get the rug pulled out from under them (if Django's bundled jQuery and your bundled MooTools each want to bind '$', who wins?).
If the admin's going to move to using jQuery, these are the sorts of questions which need to be thought out, planned for and answered very, very thoroughly first.