Is there a way to release an HTML5 game that isn't open source (viewable code)? Other than obfuscating the code isn't it necessarily available to the user?
You can wrap it up inside a web view and deploy as a native app. This is what frameworks like PhoneGap are for. Given the game is available in the iOS app store, this is probabably what they did, assuming they didn't write their own wrapper application.
obfuscating the js would still be more important, as there are probably some simple hacks to get all the javascript back from the web view or the js file used by the app.