So lets takes drakks context to heart here. He may have been to the system. But who's to say they didnt have an oopsie with it moved it if it was a handmade system to accomidate the darkwheel raxxla and the parent star system to the objects and they put it in the wrong position by accident. So we need a cross reference of the classic galmap to the current galmap to see if a system truely just upped and vanished or moved. Thats the issue going on here. I have a feeling It doesn't move on its own but fdev moved it.
I think if they moved it AFTER someone ran into it for real, they would have likely dropped something about it. Either Drakkster didn't find what they think they found, or it's probably still where it's supposed to be. There are some very seldom visited places in the bubble. Who's going to wander around some uninteresting system that has been FSS'd and there is nothing of actual value in there? Particularly if there is no fuel and it's an "uninhabited" anarchy system (so you're not going to sit around there for signal sources or anything like that).
Sounds like it's actually further out from the entry point than I initially thought based on their story - now it's meant to be ~5k LS out (so let's be generous and say anything 4k LS and further). That means you don't just jump into the system and get this finding, You have to actually go out and travel to the planet to get anything.
Now here is the real question: most of the bubble has been DSS'd at this point. It's exceedingly rare to not run into a DSS'd system. So what gives? How come whoever DSS'd the system didn't run into this?
So here the explanations range from:
1. It's moving between systems (this isn't consistent really with the story because the story implies that the planet was named and system had TDW faction - this would be inconsistent with BGS - however, this is weird scenario because we're assuming this is an uninhabited system in the first place - so you have an uninhabited system with a faction - not sure if there are other cases of that).
2. You can somehow not trigger the warning (would being friendly or better with TDW imply they just let you be? I bet most people doing actual scanning are allied with TDW). Heck I barely play by the standards of most people chasing Raxxla and getting allied with TDW was like one of the first things I did in the game (technically before I knew about Raxxla - I just happened to home base out of one of their systems).
3. The system has been permit-locked after the encounter (I seriously doubt they would remove the system).
4. The POI has been removed altogether (I can see that happening, but I seriously doubt it) or moved to another system (this I really doubt - if they were going to do anything with this, they would have more likely just removed it completely). One very legit option is that Odyssey update removed it when some things got regenerated.
5. The POI is not available unless some conditions are met (simplest: TDW has to be in control of the system and BGS currently has it on some other faction - this would imply that the POI is in an inhabited system though).