Sorefingers tends to exaggerate. The Southern states (and colonies) were not all "ethnically Hispanic." Georgia through North Carolina, were not, the areas where these settlers spread- Kentucky, Tennessee, Arkansas, Missouri, Alabama, Mississippi, etc. were not.
The Spanish influence was in the southwest, from California to Texas, with strong interests in Louisiana which were subsidiary to the French, however. They had some influence along the Mississippi River, but only as entrepreneurs. Florida began as Hispanic, was overwhelmed by other influences, but is becoming Hispanic again with the Cuban invasion. It never influenced the music of the rest of the south until modern times.
The fiddlers among the early immigrants were classically trained violinists???? (Ho, ho, ho)

One point he raised that deserves some support- the early settlers west of the fall line included a number of Germanic and other European immigrants. Much of their music apparently was overwhelmed by that brought over from the Isles.