This is purely speculative. On panel, Marco was getting the better of him in a 1 vs 2. Whatever happened off-panel is unclear.
- We don't know if King was in base, zoan or hybrid because it was off-paneled and as we saw in the Zoro fight, he likes to switch forms
- With the recent developments around King's defense, he may have ended up outlasting Marco even if he wasn't capable to keep up considering that even if Marco was outspeeding him, his defense could have made him difficult to damage and you seemingly needs knowledge to bypass King's defense, which Marco may not have gotten enough time to figure out with a good part of his stamina was already away from taking on both King and Queen and wasting his stamina for the samurais on the live floor
So i don't think that comparison really works in comparing it to Katakuri in terms of speed