Who wouldn’t? They are doing some of the most advanced rocket science on the planet. Of course, trusting corporations statements and research is an entire topic of it’s own. Taking Elon Musk seriously on the other hand…
Because they are a corporation that is actively littering LEO with hundreds of satellites, and fear economic retribution and/or responsibility as a consequence of this kind of information?
You see how there might be something called “conflict of interest?”
Having a conflict of interest does not mean they aren’t competent at what they do - just that they have reason to be biased against information that may result in direct consequence.
While SpaceX does launch and operate thousands of satellites, this also means that they stand to lose the most if LEO becomes cluttered with space junk. If anyone ought to be worried about space junk, it is the launch providers. If space junk becomes a problem, their customer base vanishes.
