Roddenberry seemed to choose the name Spock because he thought it was unique. Somehow, he was completely unaware of Dr. Benjamin Spock, a well-known pediatrician who had published several child care books. Those books were showing up everywhere in the 1960s, in paperback racks at the grocery stores.
Dr. Spock was also active in several protests against the Vietnam war. A famous photo taken during the series' production showed Leonard Nimoy in full costume with a newspaper, whose headline was something like "SPOCK ARRESTED".
Dr. Spock was amongst the anti-nuclear protesters gathered in Cape Canaveral in 1987, when a Space Shuttle with the plutonimum-fueled Galileo probe onboard was launched. I think he managed to get arrested.