Most people do not read Terms of Service. Well, they should.
Symantec Website TOS says
Any information sent to Symantec, with the exception of credit card numbers, will be deemed NOT CONFIDENTIAL. You grant Symantec an unrestricted, irrevocable license to display, use, modify, perform, reproduce, transmit, and distribute any information you send Symantec, for any and all commercial and non-commercial purposes.
I cannot find anything in the ONLINE BACKUP product information that contradicts these statements, including the specific TOS for the product. So this would mean that Symantec could allow anyone to access to any data sent during an ONLINE BACKUP session.
I think that Symantec lawyers should be a little more on the ball here.