Your Subie is naturally-aspirated, right? The MAP sensor is always under vacuum, except when the throttle is wide open, where it might read near atmospheric. There's nothing blowing past it, like a MAF sensor's element, so I'm not sure what you would need to clean. It's simply a nipple, diaphragm and pressure (vacuum) transducer. I don't see how oil would get into it, unless the vacuum line leading to it is downhill form the intake, near where the filter is, and residual oil might leak down the vacuum tube into the map sensor.
I would be concerned more with damaging the sensor by blasting solvents into the vacuum port. If your engine is running fine, I'd clean the electrical contacts with alcohol and apply a thin layer of dielectric grease and call it a day.
EDIT: looked at the diagram above and it looks like this thing attaches to the manifold, is that right? I'm not sure why it would have a nipple for a vacuum tube, if it's mounted directly to the manifold; however, since it appears to be top-mounted I'd say there's even less reason to pull it for cleaning. The engine will draw vacuum and tend to suck the oil AWAY from the sensor. There's a chance some fine mist downstream of the filter could be pulled into the sensor when you go from idle (high vacuum) to WOT (low vacuum), since the diaphragm will move slightly away from the engine and possibly draw in a little bit of mist. Gravity will tend to drain it back out, but it could gunk up, I guess.
I would visually inspect the sensor, using a flashlight. If all looks good, then I would call it good.
