Obscurity is a very big and important part of Information Security since attackers can't attack what they don't know exists.
This, if set up properly on your network, can make an attacker believe they are going through a firewall that they aren't, so they might focus effort on breaking into that firewall. You can also make it look like you have routing problems so that it's being routed through an external server, off the network, then back into your network. Then they might focus their concentration in the wrong place. And perhaps that other place is a honeypot, and when they try attacking the wrong system they are already on your radar, and it's game over for them.
If you have HopFake running on many machines with proper fake hops set up, and an attacker is trying to build a map of your network (which is something very handy when trying to attack), they can be totally messed up. Again, it would have to be set with realistic-looking ip's.
That's just a few ways I can think of using it.