The GNC loop runs several times per second. The desired output will consequently be increased by the working computers to achieve the target. The computer does not "dead reckon" anything.
Travelling through Max-Q in Earth atmosphere on ascent is far more dangerous.
> Travelling through Max-Q in Earth atmosphere on ascent is far more dangerous
Fair enough. I don't know enough about Orion's architecture to guess at propellant reserves, and how life-or-death each burn actually is.