Aren't some gains earned in USDs?
Either way, I don't think it matters for AML reporting purposes. Other exchanges, for instance, have daily limits that apply to withdrawals of BTCs just as they do for withdrawals of USDs.
Probably what is happening is that the service is not responding on their policy because that policy is still being developed.
"We will have a detailed Terms of Service and Privacy Policy before identification becomes an absolute requirement."
-
http://bitcointalk.org/index.php?topic=64275.0