Never heard of Leo buscaglia. Hmmm. Are you sure about him being the inspiration? Did shatner say this somewhere?
William Shatner has not acknowledged a Leo Buscaglia/Sybok connection, that I am aware of. But, then again, I am not a walking STAR TREK encyclopedia ... However, in my (minimalistic) research on STAR TREK V, via The Internet, Leo Buscaglia has been likened to Sybok,
Time After Time™ ... and Time Again. Both in appearance, and in persona. So often, in fact, that I simply took it as "given" that Leo was, in fact, William Shatner's inspiration for the embodiment of the Sybok character. Here are but a few examples of said comparisson which I've come across:
http://www.i-mockery.com/weeklies/weekly.php?type=movies&id=26
"If any of you remember who Leo 'the love doctor'
Buscaglia was, a sort of kinder, gentler, huggier
forerunner of Dr. Phil, I'm pretty sure Buscaglia
and Luckinbill were the same guy."
- - -
http://www.tulsaworld.com/archives/star-trek-v/article_d3db736c-6be7-5b1b-9b57-4190ed1b13fe.html
"... a renegade Vulcan named Sybok (Laurence Luckinbill),
[...] takes control of a hellhole planet called Nimbus III.
He does this by walking around and hugging the inhabitants
like some sort of interplanetary Leo Buscaglia, inviting
them to "share their pain" and liberating them from their
unhappiness."
- - -
http://www.jabootu.com/startrekv.htm
"Well into the picture, Sybok, a Leo Buescalia-type character, told another character that "I feel your pain."