Unfortunately Tom my knowledge like yours is based on written records that may or may not be true. The Noble file at Jackson Barracks had what I thought was the believable word of veterans of the Battle sho-shoeing Nobles fanceful tale. Noble's drummer story was getting plenty of play in the newspapers at the time of Sucession and mobilization in New Orleans.
I had a copy, unfortunately like Jackson Barracks material Katrina waters played its part--I lived in St. Bernard. Hopefully the records and files at the Barracks will be restored and you can go locate the file and form your on opinion from the newspaper accounts.
Am I to believe because Noble received a commission in the La Militia it is true he was a drummer in 1815? Was this commission sort of like a honorary degree than an actual BA. Noble was a lovable character who sounds like he was "Naturally Nawlins" but in 1861 there were a few vets around who disputed the Noble story. I read it in a contempoary newspaper account same as the stories about Noble's drumming. Which one is true, I don't know. I believed the veterans more than I believed the very aged drummer boy. The file hopefully will be saved because it did bring a chuckle to see the stories.
I know it is hard to dispute state records, especially militia ones. Since your information is from a well known historian's book it must be right too. So you posted it, though you thought it very unlikely, that Noble was at First Manassas. It is very doubtful he was at Manassas and hoefully the stories and file will be saved at Jackson Barracks, which is the reason I believe it is very doubtful he was a drummer who participated in the Battle of New Orleans in 1815.