It should be really titled "The Rebbe and the Microbiologist." Anyway, the Jerusalem Post has a nice profile on Dr. Velvel Greene. The post doesn't mention it, but one of his daughters is married to Jeff Sidel of kiruv fame (or infamy, depending on your point of view). Note Velvel's description of the Rebbe:
The Rebbe was so warm and welcoming he seemed more like a loving uncle than the spiritual leader of the Jewish world. [Emphasis added.]
Velvel, that's called love bombing. You can read about it here:
As soon as any interest is shown by the recruits, they may be love bombed by the recruiter or other cult members. This process of feigning friendship and interest in the recruit was originally associated with one of the early youth cults, but soon it was taken up by a number of groups as part of their program for luring people in. Love bombing is a coordinated effort, usually under the direction of leadership, that involves long-term members' flooding recruits and newer members with flattery, verbal seduction, affectionate but usually nonsexual touching, and lots of attention to their every remark. Love bombing - or the offer of instant companionship - is a deceptive ploy accounting for many successful recruitment drives.
And the proper designation would be "a" spiritual leader or "a major" spiritual leader.
That little Chabadism aside, Velvel is a good man. He really is brilliant, and he's not afraid to speak truth to power.