Basically because they ran out of facts, well, facts that worked for their side, anyway. The two Association employees decided that keeping their settlement money was the better part of valor and refused to come forward (Which tells anyone familiar with labor law cases a great deal indeed), one of the other two accusers who did identify herself proved to be a totally non-credible loon, and I believe the fourth made accusations that were so ridiculously trivial that even the Leftists laughed them off.