The origin of this is the funniest part.
It all started when PPP started calling Bilawal Zardari as Bilawal Bhutto. PTI officials repeatedly called him BIlawal Zardari, and PPP took offense to that (and for good reason. They shed the name Zardari because of the zillat it carries with it. That is why Zardari did not feature in the election campaign either). But then, in order to 'get back' at PTI, PPP started calling Imran Khan as Imran Niazi, apparently comparing him to Gen. Niazi of 1971. But problem is, Imran never took offense to that, as actions of Gen. Niazi have no bearing on Imran Khan of today, and the Niazi clan is a very decorated clan as well...., and that is what pinches PPP the most.
Its not surprising that PMLN joins PPP in the same idiocy, thinking they are 'demeaning' Imran by calling him Niazi by engaging in bigotry.