So basically what I want is not possible.
Ok, I have given up on using Discourse for a status page.
Here are my comments to previous replies:
Ok, so it’s bumped anyway. Not a solution. Not even a workaround. Sorry.
How do I mute the topic for everyone? Right, not possible.
Putting it in a category that isn’t in /latest is not a usable workaround. Also, it would still bump within its category, just not in /latest, wouldn’t it?
I’m grateful for your answers, but unfortunately the real answer is: There is no way to do that. It is not possible.
No mattter, I will use something other than Discourse for the status update page.