Because they aren't identical at all. Totally different contexts, totally different narrative framing, totally different on the ground realities. Kaidou beat Luffy mid raid. Luffy beat Kaidou and closed out the raid.
So what you're saying is :
Kaido will be defeated when the Raid ends
The Raid ended
Therefore Kaido is defeated
Except Kaido's defeat IS what signifies the end of the Raid itself as it is its objective.
Kaido is defeat = The Raid ends
Therefore your syllogism is wrong because its premises implicitly include the answer you're looking for.
Since "the Raid ends" and "Kaido is defeated" are the exact same things in this case, then we can replace one with the other.
So your syllogism is implicitly this :
Kaido will be defeated when he is defeated
Kaido was defeated
Therefore Kaido is defeated
So, basically what you're saying is that 2+2 = 4 because 4 = 2+2.
That's not an argument, and even less so a proof.
That's like saying "that's just how things are".