This is a frustrating criticism because people play a ridiculous game of semantics and equivocation that shouldn't be taken seriously.
When describing realism with respect to an approach to adapted fiction, rarely does anyone mean, "we're going to undermine the fantastic elements that make up that piece of fiction."
Rather, it's simply a tool for some aspect(s) of the work... as Blader has pointed out repeatedly, in Nolan's case, the world (not necessarily the character). Thus raising strawmen about intrinsically imaginative and fanciful elements- like aliens, goddesses, or viable vigilantes- is an intellectually dishonest allegation... as if there is, or should be, no difference or preference between Batman '66, Batman: TAS, and Batman Begins simply by virtue that viable vigilantism is unrealistic. That's an absurd argument devoid of value since there are reasons to recommend any of those approaches over the other... but the fact that viable vigilantism is fanciful has no bearing whatsoever.
So again, here, Blader is describing the application of the tool to the world, not necessarily the characters... but Rooster is equivocating a relatable world to relatable characters (which may be part of it, but not explicitly stated in the post). Part of the reason that Kingdom Come has as powerful an impact as it does, is because Alex Ross painted off of photographed models in that Norman Rockwell
hyperrealism approach. Compared to other comics artwork at the time, Kingdom Come was far and away realistic visually, but nonetheless did not, necessarily, need to betray Superman as "awe inspiring"... in fact, the story is precipitated by the idea that Superman's exile causes the heroes to retire or darken.
And, in fact, I doubt you can find any Superman that isn't relatable on some level. Kingdom Come is about being hurt when reality doesn't meet your ideals, trying again but seeing your good intentions go awry. All-Star is what you would do with your last days on Earth if unfettered by normal constraints. Etc.
Of course, the internet lacks nuance and tools like "realism" and "relatability" get ridiculously reduced into "realism means nothing fantastic" and "relatability means no awe or inspiration."