As someone who took classes with this prof, he actually never claimed the 12-bar blues came from Bach, he claimed jazz musicians stole the ii-V7-I from Bach and only got the 12-bar blues from classical musicians (he was completely wrong on both fronts*)
real shit a white professor named mark rimple at west chester university said to me once btw. fuck it man i haven’t gone there in years and afaik they’re still teaching his textbook as the theory curriculum so idgaf