I see it the other way, a luxury that you can swing him forward because the backline had everything covered.
Seeing as we are going in with Sandilands in the ruck and Tabs backing up, when tabs goes into the ruck, having the chance to throw Johnno forward keeps some forward line structure.
McPharlin has been sent forward in the last, Harry Taylor at the cats, even McGovern at the Slime has been sent forward on occaision to help out, Even though he started out as a forward he is a pretty decent defender..
Flexibility, you can't be a one trick pony in the AFL.