@tusharhero Looking back at the original post at https://petrous.vislae.town/@Binder/116981644135959252 there is no mention of *GNU* Emacs. It's a generic reference to Emacs, and it proposes that Emacs was designed for Linux.
I read that as referring to the entire family of Emacs originating in 1976, not specifically GNU Emacs or any other particular later development, and judging from the rest of the dialog on that original thread, that seems to be a reasonable interpretation.
As for whether Linux is an operating system, we could reasonably debate technical interpretations of the boundaries of what qualifies as an OS or family of OSes for days. In common parlance, Linux (or GNU/Linux if you prefer) is understood by the general public as an operating system, and that's more than adequate when writing a snarky reply intended to elevate the already humorous facepalm post from @Binder.
I apologize that I came across to you as rude. I only intended to document how I arrived at my understanding.