@Sengokusgoat:
His support has been key multiple times though. Even Kaido himself is saying his abilities are throwing him off.
Yeah, but I don't think he can keep up with either Luffy or Kaido to be of use, and Shambles is already getting old. Plus, I think we need space for others like Yamato to join in and keep the fight interesting.
This is less story and more Oda just moving on from Ope Ope tactics against Kaido. He's already drawn everything he could regarding Law facing Kaido.
@Deicide:
Thee story would let us know it if it was the case. Last page showed Law in a far better condition than Zoro. He wasn't even dirty or bleeding like really damaged characters are often presented.
Again, this is less story reasons and more Oda's personal ones. If he wants Law away from the battle, it's because he's already made every interesting decision involving him in the fight. He needs room for new characters to butt in.
When Kaido renders the vast majority of Law's moveset useless because of Haki shenanigans, there's not much he can do.
Otherwise, Luffy could've just told Law to send Zoro below while he remains (akin to the Samurai). Or Law could remain in the rooftop and treat Zoro. But Oda is setting up Law to leave.