Don't understand how Shadow Redundancy in Exchange 2010 work

I've reading Shadow Redundancy article from Microsoft site:
http://technet.microsoft.com/en-us/library/dd351027(EXCHG.140).aspx

Question 1: In the document, it gives an example of "Multiple Hop Scenario", the step 3 says:

3.The Chicago hub queries the New York hub for discard status and receives the discard notification for the message. At this time, it can remove the shadow message from its database. Whether the message was delivered from London to Dublin doesn't have an impact on when the Chicago server deletes the shadow message.

Why "whether the message was delivered from London to Dublin doesn't have an impact on when the Chicago server deletes the shadow message"???

It seems to comflict with the Microsoft definition of "Shadow Redundancy" saying "With shadow redundancy, the deletion of a message from the transport database is delayed until the transport server verifies that all of the next hops for that message have completed delivery"

it clearly says that the deletion of a message until verifying that ALL of the next hops for that message have completed delivery!

Anyone can help to explain that?

Thanks in advance,
Jerry