Wrap rye in plastic or aluminum foil

I've been making some dense rye breads from The Rye Baker.  My question is why is it recommended to age some in plastic (Westphalian Pumpernickel) and others in aluminum foil (Ammerland Black Bread).  Is it because the first contains only rye while the second contains some malt syrup and seeds, or is it just tradition.  If there's a reason, can someone explain?

Thanks and Happy baking.

Len