I would say it shows a great deal of respect for each other but above anything else, Burr respects his reputation and Burr knows that there’s a possibility of backfire and doesn’t want this blamed on him. Aaron Burr was always a very cautious man and never really fully supported one thing publicly knowing that he could’ve gotten backlash for it.
After Lennon's death the idea of reunion practically vanished.
Still, Paul McCartney, Star and Harrison got together during their work on "Free as a Bird" (which included the vocals of the late Lennon) for "Anthology 1", released in 1995, and for "Real Love" for "Anthology" 2 ”from 1996.