Quote ="Boudicca"Moot, Bilko, moot. Mute means not able to speak, moot means meeting (or, in this context, suject to discussion e.g. at a meeting). I dunno, the number of people who get that wrong...
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I think in this context it was meant to mean "its already been decided."
Which is what the term's meaning has evolved into and is generally understood to mean - which is weird as its original meaning was the opposite, as you say, subject to discussion or a meeting.
Funny thing language.
Anyway, back to Rugby....