If you calculate a .1% chance of killing every human alive if you start it right now, but also a .2% chance of saving the whole of humanity, that's morally equivalent to a 100% chance of saving the lives of 6.5 million people -- in which case you're guilty of the Holocaust if you do NOT start it.

"Shut up and multiply" works both ways.

Negligible in terms of calculating the effect of the AI project on existential risk, because the other effects, positive and negative, would be so much larger.