Nawaz's support of Taliban is security risk to Pak

It’s not a sectarian problem. Taliban have massacred thousands of Pakistani civilians and hundreds of army and police personnel in Pakistan.

Afghan kharijis first started the fasad against Muslims of Afghanistan.

This is a very naive view. Taliban are nobody’s friend. They consider Pakistan and Pakistani governments NO DIFFERENT from India and America.
In other words, anyone who disagrees with their unIslamic system. This is why they had waged fasaad against Muslims of Afghanistan.
It is the same dumb view which had caused previous Pakistani governments to support the khariji government in Afghanistan. What we got in return was animosity of Afghan Muslims and spread of violence and terrorism throughout the Pakistan society.