If someone claims a Mesora then it is not a Mesora of Klal Yisroel. This is what Rav Akavya Ben Mahalalel told his son. You keep on mentioning this problem of someone ‘claiming’ a Mesora and the discussion goes on about a Mesora of Klal Yisroel. This is not a conversation.
Nobody can force anyone unaware of a Mesora to become aware of it. But when there is a known, universally accepted Mesora, then we argue that it is binding.
You also talk about how a Mesora can’t be something unfounded. Yet you agree that a Mesora can be the Psak. You said that the original topic here, Daas Torah (whatever that means at this point), has sources both ways. So what is so different about quoting the way our Mesora is on this topic from the Mesora on any other Mesora-defined Halacha?
It’s one thing to agree to disagree, but first you have to agree on what you’re disagreeing.