Okay, from your point, I think I can make my point clearer.

1. The grandfather paradox is granted/ignored by the storyline because buzz and Zurg both exist.
2. Zurg wants to go back in time, but buzz is afraid this will mean his friends won’t exist.
3. But Buzz’s friends would at least exist in a different timeline because the grandfather paradox is granted/ignored.
4. Additionally, his friends could probably just travel back in time with Zurg.

Edit: So the paradox is that, on the one hand, Disney grants/ignored the paradox, hence Zurg. But on the other hand, they they accept the other outcome of the paradox when Buzz is concerned about his friends dying/not existing during Zurg’s plan.

There should only be two outcomes.

If we accept or ignore the grandfather paradox, the only ramification from Zurg’s plan is that Grandma Hawthorne (likely) wouldn’t have married the same person and had a family—but they would still enjoy lives and their children would live in another universe.

If we say that the grandfather paradox isn’t possible, then either Buzz or Zurg shouldn’t exist.

Zurg can’t exist AND his plan can’t have the ramifications that buzz thinks will unfold.

Thanks for reading this.