There might have been some added incentive for Kirk to own a Commodore:
I quoted this back in December ...
http://www.trekbbs.com/threads/commercials-featuring-star-trek-cast-members.277726/#post-11386752
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Kit [Spencer]'s marketing reign lasted fifteen months, and his contributions ranged from handling the final negotiations with CompuServe to getting our Commodore magazines upgraded to newsstand-quality publications. But his most visible achievement was persuading Jack [Tramiel] to authorize a multimillion-dollar ad campaign to introduce the VIC-20 in magazines and on television. The ads featured William Shatner, who had played Captain James Kirk on the "Star Trek" television show and in the movies.
In the commercial, Shatner stepped from out of a field of stars and proclaimed the VIC-20 as the Wonder Computer of the eighties. I was our on-site marketing representative when those commercials were shot in New York. The toughest part of the shoot was finding Shatner an alien-looking sweater he could wear to look trekkie without infringing on the Captain Kirk character, to which we didn't have the rights.
Jack was involved in this search for someone to be our television spokesperson, as he was in everything that affected the company. One day he asked me, "What do you think about Spock?"
I said, "He's okay, but he might come across too cold. I prefer Captain Kirk. I think he has a broader appeal."
Later, it turned out Leonard Nimoy, who played Spock, was representing Magnavox and there was a conflict of interest, but Shatner was available. He was a good choice. Not many people recall Leonard Nimoy in those Magnavox commercials, but a lot of people recall Shatner introducing the VIC. Our ad agency was Kornhauser & Calene.
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Michael S. Tomczyk,
The Home Computer Wars: An Insider's Account of Commodore and Jack Tramiel.
Greensboro NC: Compute! Publications, Inc., 1984), p 227-228.