MKS distributes for Chiappa in the U.S. and I called them this morning to ask about the 9mm Chiappa and the 9x21 listing on Chiappa's website.
The lady from MKS said:
1) MKS is not listing anything but the 357 magnum Rhinos on their MKS website because the other calibers are not even close to going into production
2) She has no idea why Chiappa listed it as 9x21 on the Chiappa website.
3) She wishes Chiappa had the Rhino in 9mm because they've been getting a lot of calls on it...
I also filled out a contact form on Chiappa's website and asked them about the 9x21 so I hope they send me an e-mail on it.