I just watched your video. Interesting idea and first time I've ever heard it.

It feels way more nuanced than that. Whatever party spending or receiving is more desperate will conceive ground on what will be accepted as payment.. many factors in that.

Im sure there have been merchants who only wanted bitcoin cash for there service.. in that instance was bitcoin cash the real bitcoin?

I think the only thing that really matters (to me) is full nodes because without a vast network of individuals running them I wouldn't trust a protocol. And without trust any protocol is worthless.