“That wouldn’t make Nero the beast of Revelation though.” — hmmm... well I don’t think it would affect that — Nero, the beast would still be the beast.
Beasts who have been dead for 50 years don't really pose much of a threat. Also Paul, who was never afraid to name names, never put forth Nero (or any Roman) as the Man of Lawlessness. Finally several texts of Revelation, including the earliest one we have, put the mark of the Beast as 616 rather than 666. But, putting a name on the Beast has been favorite Christian parlour game for eons and that's not gonig to stop.