The Wii U is no less popular today than it was then.
Yes, that's correct, except that it's not correct.
said they were committed to porting it even though the damn engine doesn't support the Wii U, now they've lost interest.
Note: The actual reason for this is that Nintendo isn't interested to provide the kind of behind the scenes development support they need and it's uncertain if they'll still be certifying releases by the the time the game is out.
I don't know why you need to project like this. If you just responded with the truth, no one would have blinked an eye. Here's the post, pre-written for you: "I already own a Wii U and it's my preferred system. I don't plan on buying a Switch or any other system any time soon, so now I can't play this game that I paid for. This is disappointing for me. I guess I'll take the refund." It's totally okay for this announcement to simultaneously be the right decision for the project and bad news for you. That sucks, man. I'm sympathetic. I hate when I'm excited for something and it gets yanked out from under me.