As getting HSTS preload ready, approved and released into browsers takes a while, it would be sensible to have ROS.org added to HTTPS Everywhere. Someone requested it at https://github.com/EFForg/https-everywhere/issues/16879 , but nobody stepped up to do it.
We did have the site temporarily redirecting to status.ros.org while it was under active migration but that was removed at the same time for https as http. My best guess is that you were encountering some caching on a transparent proxy that was not correctly setup.
I added to the https ticket to look at forcing hsts too.
You may not, but it is hosting ROS sites/mirrors. Perhaps they were previously involved in helping ROS infrastructure - they often help large projects until they are sufficiently stable and capable of self-hosting.
The hosts are listed as errors in the XML file I linked to, but I’ll repeat the obvious ones here.
The following HTTP all redirect to the status site on .ros.org
I don’t know why they were added to that list and would probably suggest that they not be there at all as there’s no web content available there nor is there expected to be any at any point in the future so it’s a waste of space in the https-everywhere database and people will spend time trying to update them or expecting them to work.