Neither the press release nor the claimant's website clarify that the "price parity" agreement is specifically about redistributing Steam Keys. If you generate a bunch of keys for your game, you're not supposed to undercut Steam by selling them elsewhere - which imo is defensible since you're selling permanent access to Steam's services.
If you're selling the game on other platforms without the use of Steam keys, there's no such agreement or restriction. I think that this changes the case considerably.