Re: "simulations" and "models", bwahaha
Well, they did once using old MCAS and got a pass on it, because the planes and systems were "similar". For some value of "similar". At one point (and maybe it's still there) was requirement where they physically bent the wings on the aircraft and test flew it.
I suspect that even if the US allows simulation testing, many of the other countries won't. Boeing was using a loophole to get around certain tests by the "Oh.. it's the same plane with mods". But real world says the modes should be test in real life.
<sarcasm> I'm sure that the air forces around the world will now rely on computer simulations when it comes down to buy military aircraft. </sarcasm>