Why do you believe that confirming suspected immunity response and subsequent protection, as is the case with so many other diseases, is in any way connected to the belief that COVID is a hoax?
I agree with that comment—that there is a mainstream narrative that says those who've already recovered from COVID still need a vaccine as much as anyone else, and that this narrative is propaganda in terms of its truth value and in terms of how it originated and was spread around—and I also think COVID isn't a hoax and that vaccines are good.
It harms rational discussion and thinking, when you take one claim and attribute additional claims the author didn't make and denigrate the author for the latter. It pushes the discussion towards a "declare allegiance to one side, attack others who appear to be on the other side" fight, and away from exploration of any nuanced position other than the two extremes—when such exploration should be one of the attractions of a site like this.