system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why didn't the Temporal Integrity Commission of Star Fleet from the 29th-century intervened when the "Narada" a 24th-century starship showed up in the 23rd-century creating a whole new timeline?

Isn't their whole purpose to prevent exactly this kind of accidents?

They did dispatch a time travel ship to pick up the "Voyager" when it was stranded orbiting a 20th-century Earth.
gpt
That particular incident (whether it be due to the red matter or the size of the supernova affecting things) created a new quantum timeline, instead of changing the past of an existing timeline as many other time incursions in Star Trek did. The difference being that the old timeline still exists - people are still running around after Spock and the Narada travelled back in time, they're just in a timeline with a different quantum signature to the new "Narada attacked the planet Vulcan" timeline. 

So, the TIC has nothing to fix - the old timeline is there, unaffected, and the new timeline is now off on its own course in its own quantum area. The new quantum timeline is not under their jurisdiction - it's under the jurisdiction of that quantum timeline's TIC, if such a branch still exists in the new scenario.