Curious Seeker ji,
Apart from the political aspect, the article does raise some questions which cannot be brushed aside.
However IMHO every Gursikh's desire definitely is to be baptised as Khalsa. So the journey from so called "Sehajdhari" to Khalsa is a continuum. Some may reach it and some may not but that does not make them any less beloved to the Guru.

Again in my humble opinion the task of a Sikh, a "Sehajdari" or otherwise is continuous self improvement and sevice to mankind which includes protecting the weak against tyranny, "Vand Chak" and propagation of the concept of Simran or Naam Jap irrespective of caste, creed or religion. And ofcoarse as Khalsa the same aims are pursued more passionately.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/sikh-sikhi-sikhism/29484-sehajdhari-sikh-federation-comments-please.html

In light of above, the conept of Khalistan being limited to a tiny geographic region appears absurd. For Khalsa the whole Earth is Khalistan.

However for the purpose of governance in India, a Sikh needs to be Keshdhari as per the ruling of the Punjab and Haryana high Court.