One little hitch with this particular theory. We all know what happened to pso2 sales the civilization that is original in PSO. Wherein we know that at some stage they made an AI to renew the environment of Coral. This AI was eventually infected by D-Cells and went rogue and killed off 90 percent of civilization. Those paying attention will remember that D-Cells, were the real reason for the Pioneer job in the first place. D-Cells had made it to Coral, via an asteroid or some such macguffin, along with the authorities wanted to weaponize it.
They put together the Pioneer job to monitor the original source of the D-Cells, and found Ragol. Going back to the first point, PS0 happens 100 years after culture gets nuked. Which is just another narrative point that runs contrary to PSO2.
I'll go through the rest of PSO2 story between what is left of Episode 2 and Episode 3. 1 last issue is the fact that it's possible... that they THOUGHT he had been destroyed. And between the occasions of PSO1 and PSO2 Dark Falz ruined Pioneer 2 while their guard was down. If that is true, it might result in being the evidence that leads to the understanding that Dark Falz cannot be destroyed. This knowledge of their immunity to complete devastation is immutable. So any Dark Falz being ruined doesn't follow the same logic as exhibited in PSO2. Another reminder is that we still have a sizable, yet undefined gap in time between the events of PSO1 and PSO2.
In short, it's likely that Dark Falz in PSO1 was just believed to be ruined despite"He's dead because we said so." His return and destruction of Pioneer 2 would awake the Oracle fleet. Subsequently, ARKS would assemble to conquer him. Then they'd then possess the understanding that Dark Falz cannot be destroyed, only sealed. Thus resulting in the event point 40 years ago when Dark Falz was closed on Ragol/Naverius. If the Photoners that met with Xion and constructed Oracle were Pioneer 3 (as explained in another thread here), it'd really still fall in line. The confirmation concerning time is that Dark Falz Elder was sealed away 40 years ago.
This calls into question several matters was sealed in a place of ruin? How did the heroes know he could not be destroyed and therefore needed to seal him? And how could they've got the ability to seal him rather than attempt to destroy him? This is solved by the notion that the Photoners Xion cites were Pioneer 3 that met with Xion. Pioneer 3 could have understood from Pioneer 2's data what Black Falz had been (and subsequently he couldn't be destroyed based on their attempts in Episode 1 and 3). Xion could lead to her being the source of the capacity to seal Falz Elder. And lastly, since Xion was their technological catalyst which allowed them to respond quickly, the heroes might have responded to the destruction of Pioneer 2 even though they were finally too late to can you buy meseta on pso2 save it.