No, the WHO was right, and still is, epidemiologically speaking. The problem is that there is a difference in meaning between "this virus is airborne" and "this virus can spread through the air via aerosols".
The former means that the virus itself can survive being exposed to the air, which means it can float for hours and spread easily over large distances.
The latter means that the virus can only survive in the air when encapsulated in a liquid, which means it can not hover in the air for long (due to the weight of the droplet) and thus not spead over large distances.
It was patently clear to everyone back then that the WHO was wrong about this.