I attempted to post a review about Chicago provider Gia Venetia.  

It was rejected because "The provider has been delisted".  This seems to be a scam by the provider to avoid accruing bad reviews.  

This seems unfair to the hobbiest community.  Why is this being allowed?  

Provider's choice as to whether or not they want to be reviewed in this site, and others. The hobbyists do not make that choice.

The fact that you have mentioned this here is already good warning that something is up with her. Thank you.