No: compression and expansion are indeed inverse operations, but you do invert an expansion into a contraction by changing the sign, you do so by using the multiplication inverse; basically, whenever you contract by a factor n, you also expand by 1/n not -n, and when you expand by k, you also contract by 1/k not -k.

Changing the sign has nothing do with expansions or compressions; in fact, if you touch the sign, you are doing, besides stretching, another transformation: reflection.