The best argument anybody has at this point is that the media narrative itself is too damaging to keep him around, but that presupposees that the median narrative is related to a specific Biden weakness and not a structural problem with our media landscape.
Yes, if we swap out Harris the "he's too old" narrative will go away because he's not going to be the nominee anymore. But I guarantee you sure as shit that there isn't going to be a new damaging narrative, either specifically related to Harris or related to the process by which he was replaced.
I'd bet anything there would be at least one narrative a bunch of outlets and pundits go with that keeps "Biden too old": they'll just claim he was "too old" when he picked Harris as VP and now that choice just has to be retroactively invalidated.
I noticed the NYT complained Biden only does “tightly controlled events,” by which they apparently mean anything other than an exclusive NYT interview. And the “granted fewer press conferences than other presidents” claim cries out for a comparison to his predecessor and electoral opponent, but no
Listening to a podcast yesterday and the person talking said "Biden isn't even doing any interviews". I yell, he's about to sit down with George Stephanopoulos. Today's episode, same podcaster, "Sitting down to do an interview isn't enough".
Keep moving those goalposts.