As we can see here - http://windows.microsoft.com/en-us/windows-vista/bitlocker-drive-encryption-overview , the bitlocker protected drive requires a cryptographic information provider like a Trusted Platform Module Chip (TPM) or another USB drive containing the cryptographic information to be present in the computer where the drive is plugged in. In our case it is the Agent VM which should have this cryptographic information provider attached.
As far as I have understood we can take 2 ways to access a Bitlocker protected USB Drive redirected to a view desktop (Assuming no TPM on the Agent VM)
1. http://www.howtogeek.com/192894/how-to-set-up-bitlocker-encryption-on-windows/ - this method will allow the use of a password or USB key (which also has to be redirected) for unlocking the drive.
2.The customer can decrypt the drive in the client side and can use Client Drive Redirection to redirect the drive to the Agent.