1. I think it is common wisdom that Khariboli possibly predates Muslim rule. Amir Khusrao likely learned it from his immediate Indian surroundings
2. Just because Khariboli has traditional had an urban orientation need not make it less "Indic" / "Hindu"
Maybe it is true that given Khariboli's pre-eminence in the Delhi region, it perhaps got persianlzed in its vocabulary to a greater extent than say Bhojpuri or Avadhi
But so what
I see that as an honorable attempt, not to be looked down upon