I don't know, I was just presenting an alternative solution to the problem you were talking about. I imagine that the sides of the encasement would have to be pretty impermeable to keep oxygen out, but it's probably harder if the oxygen-containing air is pushing in and nothing is pushing out.

Playing around with the chemistry more, it might be possible to use a gas that oxidizes more readily than silicon, so that if any oxygen does get in it will be neutralized before it gets anywhere near the silicon. I'm not sure if that's possible to do with a gas, though.