I totally disagree. Dasam Granth is different from SGGS ji for sure, with a heavier focus on social matters, literature, psychology, language, politics, culture, Indic mythology etc. etc. Repurposing traditional narratives to suit contemporary Sikh needs has also been done.
If Guru ji used narratives to explain things to Sikhs, it's on you to try and grasp the underlying themes and points of the narratives, not discard them because your own preconceptions and mental conditioning go against this.
Its funny, how people live in the cyberspace as sikh cyber warrior. Its the blind judging the blind without understanding what EGO really is. Mostly people cannot understand ego, perhaps only talking about it from what they've read. Most parcharaks, baba, jatherdars, so called endorsed gursikh within the sikh fold under the symptoms of the ego. You can only know what it is if your mind has stood still for a long period of time. This composition is very likely written by an unenlightened mind and the character of the guru portrayed in this story is also extremely unenlightened. Buddha said if you believe, it means you don't know and if you know, then you don't have to believe anymore. The theme of guru granth sahib especially from baba nanak and kabir sahib and the theme of some of the composition in dasam granth are incompatible.
A Tribute to Shaheed Bhai Kulwant Singh Ji Nagoke:
A well written jeevani of Bhai Sahib ji can be found here at this link:
Sant Jarnail Singh Ji talks about the shaheedi of bhai sahib in their speeches. If you go to speech number 12 at the link posted above sant ji directly talks about the shaheedi of bhai sahib. You can feel that love and pain in their hearts as they talk.
Also I found this clip of Giani Jangbir Singh head kathavachak at sachkhand sri hazur sahib talk about bhai sahib ji and how close they were to sant ji.
There is also a video of sant ji talking about bhai sahib that can be found here: