I'll tell you why:
1- Before even the latest introduction of Marco, SO MANY fans already paired him with King based on "similarity in DF", both birds with different flames..
2- If you want to bring up the sword argument, Oda has drawn Marco before with sword during Fishman island when we saw BB with claws, Marco with sword, and so on when WB claimed protecting FI with his name
3- The strongest points that were in Zoro's favor imo to face King was that Marco would arrive to battle LATE and making his entrance to help alliance... the reason last chapter was so bad for the "Zoro vs King" match is, NOT ONLY, Oda made Marco and King do the exact same feat against BMP on waterfall, highlighting them clashing even more
But ALSO, that Marco's introduction was EARLY before the war even starts!
Reason for this is important is simple, when Marco arrives late to battle, there is basically NO BUILD UP, whatsoever between Marco and King.... I was counting on that time Marco was absent for Oda to build tension between Zoro and King...
Where maybe during a first round of this war invasion, while Luffy gets demolished by Kaido, we also, get Zoro get overwhelmed by King
That kind of build up, before marco shows up, will make it in Zoro's favor to end King later on... cause Oda will have to redeem the first round loss of Zoro, by having Zoro return and beat him (similar to Kaku beating Zoro in Water 7, to Zoro beating him in Enies Lobby)
This makes a huuuge difference! But Marco who was already having 10times more similarity to King than Zoro does, not to mention one if first division commander of Strongest man, the other is the same for strongest creature!
The amount of similarity between both, and this last chapter added more salt to the wound by making marco do the exact same feat as King, by kicking BM ship off the waterfall
And then, we have Marco introduced early, LITERALLY before even Zoro knows how King looks like, they never met, no build up, no grudge for 3 straight acts! There is literally no encounter between the two to build their fight before Marco joins the war, to actually make the fans REFUSE the Marco vs King match, and want Zoro to get his redemption after losing a first round
So, I hope my reasoning is sound and logical to think Marco vs King is what Oda is aiming for "it seems" at least to me, personally
On the other hand, I'll repeat what I said before:
- Marco vs King
- Zoro vs Toppi Roppo
Makes sense in terms of writing
But it's not entertaining to see that as much as both Zoro and Marco exceeding their limits by fighting stronger opponents like:
- Marco helping against Yonko
- Zoro takes on King
Meaning, what I actually want is NOT what I actually expect