This is what I was thinking. I've seen similar things for perks on the S&D site in year's past. In their eyes, it's better for guests to book not expecting the perk and be surprised and get it than to book expecting and be surprised they don't have it in the case the contract is not renewed.
That said, I believe the reason has something to do with ownership. The LBV Hilton and the S&D are all owned by the Tischman Group (operated by different chains though), the company that Eisner cut a deal with in the '80s that would eventually bring the S&D to fruition.