It is my understanding then what a membership vote takes place - strike, ratify a contract, etc.. That non-votes are counted as yes votes. So if out of a 35,000 person membership, if 15,000 vote no, 5,000 vote yes and 15,000 don't vote, the measure will pass with a 20,000-15,000 yes/no vote.
In my opinion that's rather f'd up..