PTI needs to sit in this parliament until new elections. This will be suicidal.
Why would it be suicidal? They resign and ECP will have to either do by-elections or a general election. PTI will take part in by-elections and resign again if they win any seats. Causes a headache for PDM Government and ECP. There is no point validating a compromised corrupt Government by staying in opposition. People will also see that they are not thirsty for power like PDM.