> them finally employing a mm-wave radar this time is an evidence to them backing off to more "dumb" and sure to work solution as a last line of defence once their fancy imaging/neural algo fails

AFAIK from little experience in the industry interpreting Radar images is not easy nor dumb

For example read here:

http://homepage.tudelft.nl/e15f9/pdf/Uysal_MAXWELL_19.pdf