I don't think it was an issue of money, just that he didn't want to do it. Maybe he didn't think he had an hour's worth of material to talk about. I'm sure he was paid for his interviews.
The episodes Lindsey Wagner did commentaries for were for episodes she chose. I think one of the episodes was based on a plot she had suggested, loosely, and the other was a similar situation, so that was why she did those commentaries.

Lee did a lot of interviews to push the dvd's and received he said very little money to help sell them and Lee has no problems with money and is quite well off and of course still working because he loves acting so much. Lee did have a long drawn out fight with Universal and I do not know how the relationship is today and it was about Universal not honoring their contracts.

If I had to guess, I would say it was over money or lack thereof. He probably wanted an amount the studio was unwilling to pay him.