Something that doesn't seem to have been addressed so far is this:
Will all or even most TOs ban MK even if the SBR-B decides to do so? It doesn't really matter what is decided here if TOs dont enforce a ban.
Everyone is free to be ignorant.
A decision isn't just some proclamation. It's not the SBR saying "Hey guys, here's some rules." If it was, then yes, who the **** would care. On some things, we can, by necessity, take the SBR's statements on authority, since there's some reason for believing they have knowledge and, the more important, integrity.
But you aren't going to have someone just say "MK should be banned". Anyone saying it (or saying "MK should not be banned") is equally useless. The end result of the SBR's deliberation would be a statement and a
reason. That is,
reasoning.
Those reasons would make it matter, because - if they're really good reasons - it would make the statement
right. Forget legitimacy. You're right that many TOs don't think too much about the idea of legitimacy and the whole gig with the SBR for uniformity in America. But I'm going to take this to a higher level than legitimacy.
This is like law and morality. Would you say litigators don't matter too much if
there their laws won't be enforced... even when what they're investigating is what is
good?
Of those ban cases, there is one of those which is the
right thing to do, and TOs can be
judged; they are subjective to normative* terms covering the health of the game. They can fail to do right by the game.
"It would matter" because the TOs that don't line up with what is
shown would be subject to the negative terms of those norms*. They'd be
bad. That's something at stake. And this, you know, the players can notice, and alter their attendance how they see fit.
That's how it's not the case that "it doesn't matter."
*normative means "evaluative" or "of measurement against a good/bad scale of some sort". 'Norms' are the scale
(they're plural but scale is singular, I know).
EDIT: It is *NOOOOT* the same thing as "conformity" or "normalness".