This is the original phrase that has since been replaced by the obnoxious "mute point."
The first written reference to moot point versus mute point that I know about showed up in a Readers' Digest joke trailer back in one of the 1995 editions. In the joke, a father wrote in to poke fun at his daughter for saying:
"It's a mute point. I don't want to talk about it anymore."
In other words, hitting the mute button on her figurative remote control to stop the conversation that she didn't want to have anymore.
Actually, a moot is a meeting, or a theoretical case discussed by law students for practice. In strict usage a moot point can either be an important point, unresolved question, or the opposite: a question that's been settled or something nobody wants to talk about anymore.
Mute point is historically incorrect usage, although it'll probably replace moot point within a few years in common language, if it hasn't already.