Defining it as a Wi-Fi cable is a bit narrow. It's just a coaxial cable between an antenna and the router. Just make sure your cable is matched to your antenna and using the correct connectors.
You'd only need an attenuator if you're connecting two WiFi adapters directly through coax. In what is discussed here, waves always travel through the air at some point, which does the attenuation.
While technically correct, using a coax cable will reduce some dominating loss factors like multipath loss, free-space path loss, and line-of-sight loss. So, in reality, your link might improve.
I feel a little bit bad about some discussions I’ve had over the years. They could have even been more complicated(;