A couple of contemporary sources attest that while the fire was raging he was acting in a play and playing the lyre in safety and luxury.
And some others report that he was active in directing the effort against the fire and assisting with the evacuation.
It is entirely possible that he WAS acting in a play, or playing a lyre, when the first reports were brought to him of the conflagration's start. It is also possible that he delegated authority to handle the problem and remained safely out of harms way.
It is also possible that he had a bad reputation that was imputed to him as propaganda in later years because of his treatment of the Christian martyrs of Rome.
Can you imagine what history/myth in 2000 years will report about G.W. Bush and what he was doing at the time of 9-11?