I don't consider micarta porous because it is paper, linen, canvas sealed and encapsulated in phenolic resin or epoxy in the case of homemade micarta. The very surface of it may be slightly absorbent because of the exposed linen or canvas. Nothing that a good washing couldn't get rid of.
It is still my favorite handle material because it is very durable, looks good, and feels good.
I can't imagine it would hold onto scent any better than wood or G10. As a matter of fact wood would even be more porous than micarta when not stabilized. G10 is made very similar to micarta with the exception of the glass fibers.