borntobesting: Contracts these days even long term contracts can be cancelled at any time for any reason.
Here there was a definite investment in the cost of shooting the course, so I doubt the contract could be terminated at will. However, it ended an even 7 years after the course went up, so maybe it had a fixed endpoint or minimum duration. Or WGT could have effed up by allowing Oakmont holes in CC-generated mashup courses.
This is all speculation of course.
Also consider the parties' relative incentives. Besides some licence fees (which a rich club like Oakmont really, really doesn't need), Oakmont has no particular incentive to see its course used for computer-simulated golf. It's an intensively private club no doubt with a waiting list out the wazoo. It's not like the exposure on WGT is going to help Oakmont's "business" (as in a certain sense it is not a business, but is run by the members, for the members (same for Merion, Olympic, St. George's etc.)
It's different for resort courses like Pebble, Kiawah, Pinehurst, Chambers Bay, Erin Hills, Bandon.... They can use exposure on WGT to drum up paying punters. You could imagine them paying for the privilege of being on WGT.
As it stands, a valuable digital asset in the form of the Oakmont course as shot and coded and released by WGT is going to waste. It's a dead loss.
SAD!!!