He doesn't. And considering his "It HAS happened! I saw it happen, don't tell me it didn't happen!" rant, I don't really think it matters. Romulus could have evacuated its entire population beforehand and Nero would still be pissed.
I can just imagine, a few days after the destruction of Romulus. Neros wife contacts him on sub-space, "Oh, honey, that was a close call, I just got out in time before.. before.. oh it was so terrible."
To which Nero replies, "No, your'e dead, it HAS happened, I SAW it happen, don't tell me it didn't happen!" As he hits the sub-space off button and continues on his way.
Next day, Nero burns some toast in the Naradas mess hall. He throws a hissy fit and one of his lieutenants gets him some more toast, "Here, sir. I got you some more toast, lightly done, just the way you like."
"NOO, it WAS burned, it happened, I SAW it happen, don't tell me it didn't happen!!". As he throws the toast to the ground.
And so, Neros life goes on in circles of denial.