I disagree with this. Imagine if an advertising agency refused to take clients who were Chinese, Japanese and of other east Asian descent. Or if Sony required users of the Playstation Network to prove they are "non-white." How is that any different from the app that's been described? Why do you think the app isn't a "place of public accommodation"? I'm not saying it's crystal clear, and I'm not going to take the time to research it, but it wouldn't surprise me to find out that this sort of thing has yet to be litigated, and it wouldn't at all surprise me to find most courts ruling that apps are "places of public accommodation."
If you believe you have been victimized by this sort of discrimination, at least consult with a local attorney.

