Anoop ji
That is an interesting audio file of S. S. Harbhajan ji speaking in New Mexico. I listened to it when it was first posted and wondered myself.
For example, how could we know that Guru Gobind ji ate fruit and nuts and a little cheese? As a vegetarian, one would eat vegetables too, as well as wheat products. There were a lot of stories that were hard to grasp. Another thing I remember was that Guru ji was short and had very small hands and feet, but his hands were very elegant.
Probably most of us think of Guru Gobind ji as a musician, poet, inspired religious leader, leader of a people, brilliant warrior, loyal friend, devout "son" of the Gurus before him and manifestation of the presence of Waheguru. So information about his diet and feet can take a person off balance.
My thought is that there may be primary historical documents in India that chronicled his life... letters, personal memoirs, chronicles, official records in the courts of his many friends that commented on him personally. We just don't know about it because we don't have access to the documents, and aren't historians or journalists and wouldn't be even looking for that information.
It didn't bother me, but it did puzzle me.