Should this site be hosting a WP plugin repository?

Under GPL you can distribute software as long as you keep that same GPL license

So wordpress doesn’t have any concerns about this? I would have thought a wholescale copy of a repository, with near identical look/feel, and the potential to use it to spread malware/spamware etc. and damage the WP name, would be cause for at least mild alarm.

There is no trademark violation as far as I can tell. You can contact the foundation if you want https://wordpressfoundation.org/contact/

Ah, perfect. Thanks!