Making me look up "ad baculum" isn't much of an argument.
What I notice about Taylor's account is that what the German says was tactless and inappropriate at the time but it doesn't seem all that wrong or cruel as a general statement:
This person, with the strong accent and idioms of the Fatherland, comforted me by assurances that we of the South would speedily recognize our ignorance and errors, especially about slavery and the rights of States, and rejoice in the results of the war.
People who quote it tend to assume that it's all about the cudgel, but that's what they read into it. Taylor himself comes across as wry rather than bitter or outraged.
FWIW, I have read (but not confirmed through research) that one of the textbooks used at West Point acknowledged the propriety of secession under certain circumstances. Perhaps another observer could offer more insight (and citations) on this point.
I believe Rawle's book was used in 1826, or possibly from 1825 to 1827. More here. Of course once someone remembered that it had been used, other people "remembered" that they'd learned it too, even if they hadn't.
You know all those Southron types. As far as they're concerned, quid quid latine dictum sit, altum videtur.