Agent Quigley and the Callums

In a footnote to chapter 4 of Let Justice be Done, author William Davy states: "As for Special Agent Quigley, he quit the FBI in early 1964 to go work for a wealthy Right Winger named A.W. Cullum. Remarkably, in 1966, both Quigley and his wife left for a two-month trip behind the Iron Curtain. See NODA memo from Gary Sanders to Jim Garrison, December 11, 1967."
According to Forrest Sorrels, AW Cullum was President of the Chamber of Commerce, and participated in meetings dealing with the motorcade route and the location of the luncheon 
Mr. STERN - What was the next event in your advance preparations for the President's trip?
Mr. SORRELS - On November 13, Special Agent Winston G. Lawson, from the White House detail, and Mr. Jack Puterbaugh, had arrived at Dallas the evening before, and they came to my office, and we then went to the office of Mr. A. W. Cullum, President of the Chamber of Commerce, and we then went to the Trade Mart, and then to the Women's Building at the State Fairgrounds.
As we all know too well, nothing is ever that clear cut in this case. According to Win Lawson, the man's name was Robert Cullum.
https://maryferrell.org/showDoc.html?docId=1134&search="robert_cullum"#relPageId=637&tab=page
Robert Cullum was the owner of AW Cullum and Company. Presumably AW was Robert's father.
Some further background on Robert from the Irving Daily News, June 13, 1973 {bolding mine):
Robert B. Cullum is chairman of the board of Cullum Companies, Inc. He is a recognized leader in the national suparmarketing industry, having served as president of the Super Market Institute in 1966 and 1967. He is a graduate of Southern Methodist University. Directorships include Blue Cross/Blue Shield of Texas; Dallas Federal Savings And Loan Association; Dallas Power & Light Company; Dr Pepper Company; National Association of Food Chains; Republic National Bank of Dallas, and the Western Association of Food Chains. Civic activities and honors include the Lions Award for the most outstanding civic contribution in 1962, outstanding salesman for 1962 by the Dallas Sales Executive Club; Headliner of the Year for 1964 by the Dallas Press Club; president, State Fair of Texas; president, Dallas Citizens Council; director, Dallas Council on World Affairs; director, Ncrth Texas Commission; director, Texas Research Foundation; trustee, Collier Speech and Hearing Center; trustee, Children's Medical Center; trustee, Southwestern Medical Foundation; trustee and member, SMU Board of Governors; past president, Dallas Chamber of Commerce, Salesmanship Club of Dallas, Cotton Bowl Athletic Association and SMU Alumni Association. 
More on other Callums and the company here: https://www.newspapers.com/newspage/62039321/
Was Robert/AW related to A Earl Cullum, Jr who had longstanding associations with WFAA, MIT, MSU and who, during WWII, was associate director of the Radio Research Lab at Harvard, and a consultant to both the US Office of 
Scientific Research and Development and the National Defence Research Committee where he oversaw the development of electronic weaponry and radar jammers? This brief bio https://www.nap.edu/read/1384/chapter/20#107 lists all these achievements, and notes that he too, was a member of the Dallas Citizens Council and the Dallas Chamber of Commerce.