They removed it a couple of weeks ago but it still shows in my purchased list.
Thats odd. Wonder why I dont see it (on both my devices only one of which is iOS 11).
Edit: just tried again. Must have had a typo when I was looking. It does show up on my iPhone, which is iOS 11, but cant install it, of course. But doesnt show up on my iPad Mini 2, which is still on 10.3. Must be one of those apps that is completely iPhone only like SE has a few of.