Well, since neither Apple's answer nor my answer is satisfactory to you, why don't you just try it? Change your billing address to another country, change your Payment Option to None, and then change your country. See if you can still access your Apple Music. Then you will know....
But I can't see what could possibly be ambiguous about the bullet item I cited. Things that you added from a previous country's store will not be visible.
The general advice we provide to anyone asking about accessing media purchased in another country is to make sure that they have downloaded that media to their iTunes Library. That is the only way to ensure that you will have access to any media associated with a different country's iTunes Store. And that is only for items you purchased. Streamed Music isn't even available if you aren't on Wifi, so if you change your store, then I have no clue why you would think that the bullet from that article would not be correct. It's common sense.
Good luck. I'm out.
GB