"gnu.org" is on the list marked as a Chinese website...
nature.com is marked as Chinese, as are nginx.org and ntp.org.
example.com is Indian in the list as is the now defunct dmoz.org.
I don't understand the methodology behind the country assignments at all…
I was also wrong to say that w3.org never redirects to HTTPS. If the browsers sends a Upgrade-Insecure-Requests HTTP-header, then it redirects. That allows it to support all browsers as securely as possible.
Sites like whynohttps.com and observatory.mozilla.org should really test for this pattern.
% curl -I senate.gov HTTP/1.1 301 Moved Permanently Server: AkamaiGHost Content-Length: 0 Location: http://www.senate.gov/ Date: Tue, 17 Dec 2019 10:37:04 GMT Connection: keep-alive
% curl -I www.senate.gov HTTP/1.1 301 Moved Permanently Server: Apache Location: https://www.senate.gov/ Content-Length: 231 Content-Type: text/html; charset=iso-8859-1 Date: Tue, 17 Dec 2019 10:37:08 GMT Connection: keep-alive
It seems to meet the requirement for exclusion from the list. Data updated 16 Dec 2019, so I don't think it's stale.
I've also checked from Australian and a European connection, so I don't think it's a regional thing. The other genuis.com doesn't work for me, the other sites redirect and set a cookie.
Maybe their tester applies the same criteria - although to me that feels a bit unfair...
Must be a bug.