Zelnick, 73, was sentenced to three years probation on the misdemeanor charge, The Boston Globe reported Thursday.
He also was found guilty of failing to yield, a civil infraction, said Assistant Plymouth District Attorney Bridget Norton Middleton.
Zelnick turned his sports utility vehicle into the path of a motorcycle driven by Brendan M. Kennedy, 26, of Plymouth on Oct. 7, 2011, authorities said. Kennedy was unable to avoid colliding with Zelnick's vehicle and died from his injuries.
Zelnick knew Kennedy, who worked at the golf club Zelnick had just left.
The judge also ordered Zelnick not to drive and to write a letter of apology to Kennedy's family, said Zelnick's attorney, Raffi Yessayan.
Yessayan said Zelnick was not speeding or under the influence at the time of the accident but was convicted because "given his health condition at the time, he should not have been operating a vehicle."
Zelnick had not driven since the accident and would not drive again, the attorney said.