I'm not sure whether or not oxygen is needed for the sort of yellowing in Amigas. Plastics differ chemically, so, I suppose it depends on the kind of plastic and the yellowing process that affects Amiga plastics.
We apparently DO know that UV light is a factor in yellowing of Amigas (and the later Commodore 64Cs and 128s)... so I suspect keeping your computer out of sunlight will be quite effective. Either keep it in a room away from the window, or put an opaque cover over it when not in use.
Assuming this stuff doesnt ruin the look or feel of your Amiga, there's probably no harm in trying to see if it helps.
