So the source code becomes an item that people would want to buy, but is not possible to sell or even donate? All that remains is destruction, at least if it contains fragments of Activision IP.
I do not see why he could not donate these materials to an institution -- even if they could not make them available straight away.
I once worked at an archives that held sensitive records that were access restricted for 100+ years. Someday, all of the people whose privacy interests are affected will be dead, and then the records can be made available.
Similarly, Activision's copyright will eventually expire; it is just a matter of waiting long enough. People die, but public institutions can last forever, so that is an argument for transferring material to an archives or museum. YOU may not live long enough to gain access to these materials, but future generations will.
I am unfamiliar with American tax law, but, in Canada, such a donation to a public institution would be rewarded with an income tax credit for the fair market value of the donation.