The biblical namesake is female. I can see someone just hearing the name and not knowing the history wanting to use Keziah for a boy because it is similar to names like Isaiah. I wouldn’t do it, but I wouldn’t be shocked if someone did.
There's a female namesake, but she was named after a tree...tree names are usually either masculine or unisex in my culture...It might be kind of like a male Hadassah or Myrtle, though. That'd be at least a little odd.