This might have been made before modern NDAs and all the IP documents you handover when you join a tech shop today, or maybe Ken and Roberta W made some special deal with him since he was there really early on with the company?
Even if that's not the case, there's a good chance all the original contracts were lost too. I mean, it really all depends on if Activision (or whoever currently owns the original LSL/Sierra IP) finds out and decides to come after him.
In the US, it's called the First-sale doctrine: https://en.wikipedia.org/wiki/First-sale_doctrine