Update your dictionary.
Could you please spare us the whole thing about outrage culture and all that shit.
A promise would be: "We are undoubtedly releasing this game in this platform. Back us and a Wii U version will definitely be a thing in the future!" That's a promise.
Saying they are working on a Wii U build is not they promising it wil come out and that it isn't going to be cancelled at some point.
I mean, if it is, where it's the outrage at the PS3/360 versions being cancelled? Where the the people screaming "muh broken promises" on threads about cancelled games/versions?
And no, it's not, "the whole thing about outrage culture". Most people here didn't back the game at all and are acting like the devs killed their dog or something. Without having any personal stake on it at all. Meanwhile you can go the actual game's forums and see that actual backers that only backed it because of Wii U are an extremely small base of it. And those that are, they can still ask for a refund, or they can be smart and just wait for August to get all the money they invested back and some profit on top. They can be outraged, never back one of the dev's projects again, but this is a non-issue all around.