A prison inmate was engaging in expressive conduct protected by the First Amendment when he went on a hunger strike, a federal judge has held.In a written opinion this week, U.S. District Judge John Robert Blakey did not rule on the merits of Kevin Birdo’s allegation that he was the target of retaliation at Stateville Correctional Center for conducting the months-long hunger strike.But Blakey reaffirmed a previous ruling that Birdo was conveying a message — his objections to a delay in medical treatment and …