That’s kind of like the Nazis being welcomed as liberators when they marched into Czechoslovakia (and I’m not talking about the Sudetenlad). No doubt there were a few Nazi sympathizers, and no doubt there were a few Czechs who were terrified of the occupation and “went along to get along.” But “maifesting great delight?” No way. Ditto with the Yankee occupation of the South. To subscribe to your belief that the citizens of the Confederacy were wild in their happiness at being “liberated” by the Yankees one would have to believe that those citizens were wild with joy and happiness that those very same Yankees killed their sons and brothers and fathers. Not only no way, but no f***ing way!
Certainly there were variation across the South, but there is ample proof of widespread regions of real pro-Union sentiment A more high profile example is the heroes’ welcome received by Burnside as liberators of Knoxville. It depended on local and regional sentiment. I’ve read a midwestern Union soldier’s account of the the marked contrast in citizen sentiment after crossing the Cumberland Plateau. Widespread Southern hostility was replaced by a welcome feeling of being at home among appreciative friends. A lot of southern people believed they had much more in common with the midwestern Yankee farmer/soldiers than they did with the under-worked members of the decayed aristocracy who ran the Confederacy.