I'm fairly certain that you would be penalty fared if caught though as its no longer valid via that route.
Oyster doesn't have defined routes (except where there is more than one fare for a route). So long as you touch in, have enough Zones and PAYG to cover touching out at any point you may pass through on your journey and don't go outside the Oyster area or over the time limits for your journey you may take any route you like.
If you've seen it documented anywhere that this route is no longer valid, I'd be interested.