Re your post, JFK was first (to thank Jews for his political elevation). Warren Bass's Support Any Friend is a very good book. The episode you quote however is only the beginning of the JFK-Ben Gurion relationship. Read chapter 6, "The Delicate Matter: Kennedy's Struggle to Deny Israel the Bomb," especially the section beginning on p 211, "Kennedy Goes Nuclear." By May 1962 (after the midterms) he had had it with Ben Gurion:
Then came the bombshell. As Kennedy had noted in his May 8 press conference, "we have a deep commitment to the security of Israel." The United States supported Israel in many ways. "This commitment and this support," Kennedy wrote, sticking in the shiv, "would be seriously jeopardized in the public opinion in this country and in the West as a whole if it should be thought that this Government was unable to obtain reliable information on a subject as vital to peace as the question of the character of Israel's effort in the nuclear field." One could almost hear the Foreign Ministry gasp. (p 216)
Kennedy was a politician, but he also was sincere in his concern for and determination to achieve not only Israeli but more important, US security. He also was willing to take whatever repercussions this harsh stance against Israeli stonewalling would bring down on his head from the lobby, which every president since FDR has had to deal with.
Recall also that Kennedy had just faced down his entire JCS and CIA warmongers on Cuba. JFK was a mensch.