The comments here are missing the real issue - its the inconsistent application of the private API rule by the app store teams that is arguably the worst part of this. Apple have a terrible track record in consistent application of App Store rules. I'd argue there's enough evidence now to support a theory that some apps are considered just too important to reject.

When will they pull big Electron apps like Slack et al? I'm guessing never. It's often the little guys whose business gets stomped on by the unfair application of these rules.