These are not good signals to be sending when you're trying to get a contract to send a manned mission to space.
The article itself says the theory isn't completely kooky. Quote: This is not as crazy as it sounds, and other engineers at SpaceX aside from Musk entertained the possibility, as some circumstantial evidence to support the notion of an outside actor existed. Most notably, the first rupture in the rocket occurred about 200 feet above the ground, on the side of the vehicle facing the southwest. In this direction, about one mile away, lay a building leased by SpaceX's main competitor in launch, United Launch Alliance. A separate video indicated a flash on the roof of this building, now known as the Spaceflight Processing Operations Center. The timing of this flash matched the interval it would take a projectile to travel from the building to the rocket.
This seems a wildly broad description, doesn't it? What interval, for what projectile?
SpaceX saw a weird coincidence that might be worth investigating. Thats all you need to know.
It's completely kooky, so kooky in fact, there's a (IMHO very funny) sketch about turning business competition into a gunfight: https://www.youtube.com/watch?v=mpC_hO15IoA. It's funny because the idea is so absurd.
United Launch Alliance has lawyers. Blowing up your competitor's rocket with a gun would be about the stupidest thing you could possibly do. The upside is low (single rocket launch ruined), the downside is massive (huge civil and criminal penalties). It also suffers from the typical conspiracy theory weakness: everyone involved would need to keep their mouths shut forever, and realistically, at some point someone's gonna have loose lips.
Not commenting on the overall viability of shooting a rocket by competition (it would be stupid IMO), but it's not just a single launch ruined. Launch failure can stop launches/production for months (3-4 months in this case, 5 in the case of the previous SpaceX failure), or even longer if finding the cause of the failure is very hard. A pause in business like that can destroy a company that needs cash. Also, it reduces customers' confidence in the failing rocket, which would be good for the competitor with a flawless record.
Compare that with Boeing's MCAS problems, the plane crashes themselves were less financially damaging than the resulting groundings, production pauses and canceled orders.
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".
They did that too. They didn't only research in one direction.
The reality is that this was a incredibly unique thing that had never been seen before. So it took longer then most investigations.
Of course they didn't understand what happened right away, in fact, it would have been worrying if they did. What did you expect? Something like: "Oh yeah, it was a leak, it happens sometimes, we just hoped that it wouldn't go boom"?
The focus on the sniper theory is just one of Elon Musk's ramblings. Good thing SpaceX is not just Elon Musk.