system
Given the following post, respond as if you're commenting on Reddit:
human
[Dragonball Xenoverse]If the Time Patrol is supposed to stop people from meddling with history, why didn't they sabotage Trunks' time machine or prevented him from ever meeting the Z fighters in the past?

That would have also eliminated the threat of Cell coming back due to the time machine never being available to him.
gpt
Maybe Trunks' interference leads to the formation of the time patrol, so they can't undo it or else they won't exist do undo it. He's like a universal constant that has to happen, it's other aberrations that must be stopped.

Like in Dragon Ball Super with the additional time travel shenanigans, maybe those things are supposed to happen for some reason only the Supreme Kai of Time knows. She helps guide the Time Patrol and prevents them from undoing anything that HAS to happen. Fixed points in time and whatnot.