How about dropping HTTP and the "archive" feature?

[filler56789]

1) Google is stupid and indexes the pages through plain HTTP and not through HTTPS. The problem is, the HTTP interface doesn't show that the users of this forum are logged-in;

2) Google is stupid (always) and indexes many pages of this forum through the "archived" versions of those pages. And as "everybody knows" :sly:, the "archive" pages contain only text, no links, no images, no attachments, and become a nightmare when the thread is huge;

https://forum.doom9.org/archive/index.php

[Ghitulescu]

I don't think it's important to know whether somebody is online or not. It's a gimmick.

[filler56789]

I don't think it's important to know whether somebody is online or not. It's a gimmick.

Obviously you missed the point.
If you set doom9.org to "remember" you "until the cookies expire", you'll find that you are not logged-in in the non-secure version of the forum.
If you think this "detail" is irrelevant too, then it is a different story of course :)