Regardless of the reason, if Electron was using private APIs, and Apple doesn't allow Apps that use private APIs in the Mac App Store, I'm glad Electron isn't being given a free pass just because it's popular.

If this was iOS, where sideloading is basically impossible, I'd be much more sympathetic to the author's view. But we're talking about the Mac. Apple's quality control is the reason for users to choose the Mac App Store. Any users who don't want that control can easily go elsewhere.