Woodle Tree Adventures - Soundtrack - loophole to give away free game?

There's no loophole. When creating a giveaway, you have to pick the product you are giving away. If you pick 'soundtrack' when you are giving away the 'game + soundtrack', you're picking the wrong product, even if in the end you're giving away more than what you selected. So all those WTA soundtrack giveaways are breaking the rules. No loophole.
The soundtrack DLC hasn't been given away for free, so there's no reason to remove it from the list.