to be very honest, political differences aside, PMLN has achieved what it wanted from this whole episode.
NS had to come back with MNS, so they made the most of it, generated some political activity for their party, wanted to be arrested themselves so that they can play the victim card, captured media for 2,3 days completely and seems like in coming days as well... Just think that other parties rallies and speeches/programs are all set aside now and only NS is being discussed. Also they never wanted too much trouble on streets with arrests and agitation etc, on one hand that might have deprived them of political workers and on the other hand people might not have liked any property destruction.
Last but not least, NS wanted to save his property and strike a deal, which seems like also achieved.