Nope, AE's background renderer chokes when it gets a CS5 file. It needs to be converted to CS6, which is fine if you're using the GUI -- it'll prompt you to convert it when it opens it -- but if you're skipping that and going straight to the render it won't do it for you. You'll have to either convert it to CS6 or set up a CS5 watch folder.
At least, I'm assuming that's the case -- I haven't used watch folders in years, but that's how the command-line renderer works, which I assume is more or less the same thing.