Yeah this is bad.
It's not a one time activation.
I had an "activated" disc, which worked fine offline.
I uninstalled that disc.
Reinstalled the disc.
Now it needs to activate again.
I didn't even restart the console.
Again, maybe an issue caused because my console isn't my home console but it shouldn't matter.
I'm assuming this is less 'an activation' and more that it needs to download a small config file or similar to make the thing work on a console it was never designed to work on. Deleting the game would (should) delete all files associated with it. I would assume that, yes, you'd need that file again if you tried to install it after deleting it.