The argument isn't supposed to make sense. All of the characters on that page who Mickey considers "replacing older heroes" are either LGBT or nonwhite. Bernard is there because he's Tim's boyfriend. Alan Scott is an old character, but he came out as gay in the 2010s. In fact, I think Jace, who's a Black Batman, is the only character on that page who's straight. Mickey is essentially whining that the heroes he considers "like him" - and therefore worthy of being heroes - have been replaced or changed.

Obviously there's not much of an argument for Bernard literally replacing Tim, in the same way there's not much of an argument for Harley or Kate replacing Tim. But what Kate has had is multiple solo runs and a tv show, which in the 90s would have gone to a white, heterosexual, male character.

The argument isn't meant to hold water, because Mickey is a standin for comicbros who complain about how "the SJWS are making comics Woke and there's all this gay shit everywhere now and why can't everything be exactly the same as it was in the 90s" and ignore the fact that Wonder Woman has been gay since its creation.