After a judge ruled a panel can move forward Saturday at the University of Massachusetts Amherst on “Israel, Free Speech, and the Battle for Palestinian Human Rights,” we speak with one of the event’s scheduled participants: Roger Waters, co-founder of Pink Floyd, one of the most popular rock bands of all time. He says he welcomes the lawsuit that challenged the event, because “what it does is it serves to shine a light on the predicament of the Palestinian people.”