Yes, I've seen the comments you're referring to - can't remember if they're in the book YEAGER or elsewhere. There was certainly a tension between the Air Force test pilots and the NACA/NASA research pilots. Both Yeager and Pete Knight expressed opinions that their civilian counterparts were more interested in the technical side of research than flying and lacked the skill and experience that the Air Force pilots had. Having said that most of the civilian pilots had prior military combat experience so were clearly capable at what they did.
With regards to the XB-70 incident, in retrospect it seems foolish that a close formation flight was attempted with the wings in their down position as these created huge vortices. Also the weather was poor that day (Walker had commented to a colleague that it was 'a bad day for flying' but he had to 'get this thing done')