The subprime crisis was a story of perverse financial incentives causing the industry to play along with a fig-leaf statistical excuse for overrating derivative products, not bond raters botching ratings or missing "common-knowledge" info about specific mortgages.

If you want to suggest the subprime crisis as a mechanism for SpaceX bonds getting mispriced, you need to propose a model for how bond evaluators could be operating under a perverse incentive to under-rate it and somehow reap profits from doing so.