BCNEX gave bounty hunters an option to exchange BCNX tokens earned from bounty for XRP. Now, you cant get BCNX back. You can convert it back. I think thats BCNEX team decision to prevent dumping once listed.
The opportunity given to swap Bcnex tokens to XRP was actually given to the participants of the earned programme which is similar to airdrops and not the bounty hunters. Bcnx is yet to be distributed to the bounty hunters because the bounty is still ongoing and tokens are yet to be distributed.