As Polygon noted, the refund page surfaced just a couple of weeks after a plaintiff voluntarily dismissed a lawsuit accusing Activision of false advertising. Robert Fishel bought GHL two years after its 2015 debut, only to find out that Activision was wiping out his ability to use the "vast majority" of the game's songs. Although there's nothing official, the refund page is intended to avoid future lawsuits from Fishel (who's allowed to sue again) and other customers.
The program underscores a common problem with games that depend on internet services beyond multiplayer play: if the required service goes down, the core game breaks. Moreover, companies don't usually make a public commitment to running those services for a minimum amount of time. Gamers don't know when the lights will shut off and leave them with a fraction of the game they once had.