I think that NASA learned their lessons with the loss of crews and Space Shuttles Columbia and Challenger. 14 deaths that shut the program down. It really doesn't matter how many times you get lucky, it really matters how many times you are likely to fail and have crew losses. The real answer...
I agree ... it comes down to probability ... was a successful Starliner return only projected as a 25% chance of success and they got lucky, or was a successful Starliner return projected with 90% chance of success and they still got lucky to miss the real 10% chance of crew loss?