Wenger plays players out of position all the time, they're usually sh*t in other positions as well. Just happens this guy is good in other positions as well, makes him even more handy.
Why not indeed, Moutinho and Toualan were available earlier in the summer, but we just sat there and watched observing the waiting period. Song was sh*t yes, but then he's not a very good player, there's others who are better than him.
As I said before Gustavo wouldn't have been my 1st choice, might be my 6th choice or something....but like I said beggars can't be choosers.