I think what makes Zib’s reaction to Dib so reasonable is not only did his alternate self told him (in his viewpoint) that something was wrong with him and that he disagree with his plan because it was absurd, but this was the first time Dib actually started calling him by “Zib” because he has fully turned against him at this point.
Which is something he always hates being called.
He doesn’t mention it again, but you can tell that now being called that by his alternate self made him loose all trust and a hint of respect that he may have had towards Dib (despite just seeing him as just a lower version of himself) caused him to see him as now a full fledged enemy.














