If customers are paying BTC in to a Coinbase account, and the account holder is removing the coins as BTC, then why would the bank's policies impact anything? It's understandable, because (presumably) financial regulations mean Coinbase can't offer a "no USD withdrawal" account that doesn't have the link to the bank, but it's a shame too.

I'm certain there's a contract provision involved along the lines of "We will only provide banking services to you if you agree not to engage in or serve customers who engage in our prohibited industries in any manner."