The Equal Employment Opportunity Commission sued the large warehouse club Costco on behalf of former Costco employee Dawn Suppo, alleging a hostile work environment premised on the gender-based harassment of Thad Thompson, a Costco customer.The agency claimed that Suppo was constructively discharged in September 2011 because she was forced to abandon her Costco job as a result of Thompson’s harassment.The U.S. District Court for the Northern District of Illinois recently denied Costco’s motion for summary …