The inflatable union rat has reared its ugly head again. This time, the rat is standing (well wobbling, really) at the corner of Broad and Lombard streets in front of Suzanne Roberts Theatre, home to Philadelphia Theatre Company, which was supposed to sneak preview its new Martin Luther King-based show The Mountaintop tonight. Except that's not going to happen. (Note that tickets to the official opening next Wednesday are priced at $59.)