When viewing an item in Archive Manager with a BCC then the only mention of the BCC users email address seen is in the "Journal" tab. If a "Reply All" is made to an item in Archive Manager a copy of the item does not go to the BCC user.
Is this the expected behavior?
Yes, this is expected behavior. For examplel if an e-mail is sent to to Bob and Jane is BCC'd, when Bob clicks reply to all, the reply would be sent to the sender, but not Jane as Bob doesn't know that Jane is BCC'd.
Thats what BCC is all about, the recipient does not know if they are the only recipient. Archive Manager behaves in exactly the same way.