mute (adj): unable to speak : lacking the power of speech
A debating point which is rendered insignificant by events is a moot point.
There are things called "talking points," but those are points one wishes to talk about, not points which themselves talk. So while it is perhaps technically correct that, being abstract concepts without the power of speech, all points are mute, there is really no such expression as a "mute point."
(Must stop reading online comments in newspapers...)