If there is no problem, then a solution isn’t required.
Extractor tricks are inherently linked to Z losing drones while constructing cancelable buildings. There is no reason for Z to become the only race unable to cancel their buildings ; and their economy/drone count growth being non linear is offset by the other races’ harass possibilities and macro mechanics (Chronoboost + no probe building time loss, Mules).
This game has enough imbalances left as is to go tryin’ to fix what’s not broken, wouldn’t you agree ? 