The only thing Sabo has going for him was potentially having advanced haki. That’s no longer an advantage.
1. Sabo is Dragon's right hand man. Zoro is Luffy's. Until the end of this battle, Dragon>Luffy. Greater hype for Sabo.
2. Zoro needed a mobility assist to get to the roof.
3. Better portrayal vs. Fujitora.
4.Sabo likely has internal destruction haki, that Luffy just learned. Zoro only has barrier haki, and as of this chapter is merely repeating a feat that Kinemon has done. Being able to block someone's projectile attack is the starting line for being able to fight them, not the finish line.