So young Southerners were “radicalized” so to speak? Very interesting information.
In the C-Span conversation between Allen Guelzo and Gary Gallagher they said that Arlington and other properties were going to Lee's children, so if Lee remained with the Union, he'd likely be fighting with his children, and that might explain why Lee became a Confederate. It's also the case that Southern secessionism, sectionalism, and "state's rights" thinking had been growing since 1850 (and even earlier). I'm not 100% sure that Lee's children were ardent secessionists, but it's something that might be worth checking out.