[marcuskane2]

It wouldn't need to be some plan signed off on by ULA's top brass.

It could have been a single person acting alone for whatever reason. Plausibly an employee of ULA who formerly worked at SpaceX and was mad as mistreatment there, or mad they interviewed and didn't get hired, or mad that SpaceX was beating them at whatever and making them look bad or whatever.

Or it could have been a person unaffiliated with ULA who just found a way to access their roof.

History has a handful of pretty significant events that were basically "one guy with a rifle".