Actually, Justinian Octavius said the same above: "13th Legion's leadership were asked if Ghost Legion could take the HIP 98621 system and said yes."
This occurred sometime back, before ThePaveHawker's own effort to manipulate the BGS mechanics. As he noted, "They then changed their minds. It is not Ghost Legion's fault 13th Legion didn't bother to look up who the faction was."
The Ghost Legion's efforts were already well underway when ThePaveHawker made his group's push for a spot in the system. It seems too obvious that it was because of his intent to get the 13th into the system that the 13th's leadership reneged on its earlier agreement with Ghost Legion.
You can't arbitrarily call "bull" on something that comes from multiple sources nor simply because it's the first you've heard of it. As I noted above, I frequent ThePaveHawker's stream. I did not during any of those many instances note any awareness on his part about other PMF's operating in the system. Yet, the leadership of multiple groups with Imperial affiliation (including 13th Legion) signed off on the effort of Ghost Legion to hold away in the system.
As Justinian noted, 13th leadership removed their support for Ghost Legion's effort at some point. This suggests they were aware of ThePaveHawker's efforts and elected to support him. That they evidently failed to notify him of Ghost Legion's efforts in the system is on their shoulders. Now, I don't know with any surety that 13th leadership made their intentions apparent to Ghost Legion leadership. If they did, they did so poorly as they didnt dissuade Ghost Legion from continuing their efforts. If they didn't, then, again, the outcome and the current situation is on them.