[dragonwriter]

> but don't we have the ability to 100% simulate the rocket physics and the code it runs on in a simulation environment?

No, we don't. While we can do this very well for the "high level" physics, we can't do it very well for the "low-level" physics such as -- for one example -- the detailed effects of turbulent flows (both outside of the craft and inside of the plumbing), which are usually modeled based on averages of aggregate effects and random models because a detailed deterministic model is impractical (both, IIRC, because doing so at the level we could in theory do is too computationally expensive to do in practice, and because even our theory is pretty limited when it comes to turbulence.)

> I imagine with proper simulation this should have been catchable.

Its possible that there is some level of simulation which would have caught this (we won't know unless they figure out with enough detail what the problem was), but even if it would have been possible, it may not have been cost effective.