The seal is much like a piston ring; it is metal with an end gap. It wont be harmed by oil pushing through it.
My delete was leaving a greasy mess everywhere but I figured out the problem...If I rolled the sled and didnt completely clean the intakes of snow, it would cause a vacuum and draw the oil out of the center section through the gap. When the throttle closed, all this oil in the compressor and charge tube would get blown out the BOV as a mist and condense on the airbox underside, ultimately leaking on everything.
If your intakes get clogged or the foam is still in the factory intakes it will make a mess. No problems for me if it's cleared and I also added an slp intake for some more surface area.