I know many find contradiction with his statement saying that OS Ben 10k and OV Ben 10k are his true futures and they are the same. I get that and thought of it far too much. However, through that process I found that the statement is not as bad as most would believe nor is it really impossible. This is not to say that what Derrick said is fact nor that you should like it, just that its not a crazy conclusion.

To start off we have to go to his statement from the Ben 10k wiki: "Your 'plot holes' are irrelevant. Time isn't completely fixed, it's shifting. Events can be subtly altered. But Ben 10,000 is the future for the Ben Prime timeline."

This is not a far out there statement and the show confirms this three times;

(1) Paradox himself has admitted to the possibility of timelines bleeding into each other somehow in Ben 10k returns in UA.

(2) Then we have Eon in the same episode wanting to “replace” Ben’s timeline with his own.

(3) Lastly we have the episodes of OV where the Bens fight together. When Vilgax set off the time bomb it is said to have severely effected the timelines in the past so much so that No Watch Ben needed to intervene.

Lastly guys we have a world full of time travel where Paradox is said to have saved the world thousands of times, where celestialsapiens change the universe in ways the characters probably are not aware off, and where a time war happens.

After seeing everything I listed above its not impossible that one of these things led to OS Ben 10k’s timeline bleeding into Prime Ben’s and changed some things around. Like Kevin is not even evil in this future so the level of change is unknown. Of course this is just a theory and you can disagree, but Derrick didn't say anything out of line.