According to the Devs who ported the game they left a hardware check in to prevent oculus users from playing it because "they had not done adequate testing on the Rift"(we know that is BS though and it was really about the lawsuit), the SteamVR devs then went in and added code to SteamVR to block that hardware test by adding a placeholder for Rift users that basically lies to the game and tells it that the headset is a Vive.

That is in no way maintaining support, that is circumventing a hardware check. They could easily circumvent the same hardware checks that Oculus has in place, and that we have already seen done with 3rd party apps like Revive.