There's no "seem" about it, what you're saying is true, and it was because of changes in federal law. [0]
[0] https://en.wikipedia.org/wiki/Mike_Mansfield#Mansfield_Amend...
At the same time, when I helped with research in a cognitive psychology lab in school (much closer to the present than to that law), our PI said our funding came partly from a grant from the US Navy. We worked on Bayesian models of human learning and reasoning -- so "direct or apparent relationship to specific military function" has perhaps at times been interpreted somewhat loosely?
I'd speculate the Navy had perhaps more discretion over how it spent its research funding. For example, they funded polywell fusion research for years.
Teaching individuals quickly and at scale is a core necessity for militaries. Whether not or it gets used, the US Army usually has access to whatever is near the edge there (as in some unit or officer somewhere was promoting the method, and had the sign offs necessary to disseminate it, but culturally it was not fully put in place).