The thing is, Oda always consistent with Zoro if he using haki. Like when with Hawkins and Kyoshiro, Oda didn't give Zoro black swords. But vs Kamazo, we clearly saw Zoro hardening his weapons including the scythe to perform Rengoku, all black. With Apoo Zoro clashing haki, the swords turn black.
So yeah, in this chapter Zoro not using his haki.