If CB can't easily allow customers to withdraw the BCC, they probably can't easily exchange the BCC themselves either? (I recognize that people not being able to withdraw the coins at all is an issue, just curious also about the ability of CB to speculate in the interim).
Allowing customers to withdraw BCC involves adapting their platform to connect to the BCC network, track how many BCCs each user owns, allow them to issue transaction orders in it, etc.
To exchange themselves they only need to load their existing wallets in an existing BCC client.
