Upvote:1
Ghulam Hussain was very much biased towards his own religion and sect (I forget if he was Shia or Sunni) You can find this reference made by company official who translated his book Siar-al-mukhatarin to English. As per all existing historical records Aurangzeb was a bigoted ruler and wanted to convert whole of India to Islam by force (others were successful using peace or by Sufi movement). His policies made many Rajput states from Rajasthan, Sikhs in Punjab and Maratha in Deccan rise in rebellion. So its fair to assume that he punished Teg Bahadur for rising against him and after capture asked him to convert.
It is to be noted that he presented similar choice to captured Maratha King Sambhaji down in Deccan (read : History of Marattha by John Duff)