@gbm: MoonReader can open both schemes, file and content. It is up to the app sending the intent to MR.
But I'm repeating myself. All I can say is already on the two posts above (one in this thread, the other linked).
If some developer wants to show this is not possible and the app is rejected if submitted with a lax VM policy I'm all ears. That was not the case in Dec 19, it shouldn't be the case now.
I see why it's not a good idea (see the post linked) but being a bad idea and being impossible are two different things