In PA if both parties agree, can jointly owned property be excluded in uncontested divorce

sure.  if they both agree.  and they both understand what they're agreeing to.  buy by excluding it now, you may be asking for trouble later, when you try and determine how that propoerty is going to be distributed.  sometimes it's a better idea to do it now, when the court can assist if it becomes impossible to agree on what to do with the property.