The pin itself is not the issue.
The issue is, is David Muir a "real newsman" who is going to give it to us straight or is he a star desk reporter flying in from New York and taking a helicopter ride simply for a photo op, like others have done with major stories before him, notably Brian Williams?
Many people are questioning his neutrality this year after his performance in the Presidential debate where he "fact-checked" Trump multiple times, yet didn't do the same for Harris, even after she posited (just as one example of which he should have had first-hand knowledge) that there were no US troops in a war zone overseas (Tell that to the troops stationed in Iraq and Syria, who are constantly fired upon).
Personally, I feel that he is photo-op hound, and the clip story is small, anecdotal evidence of that; I am not making a big deal of it. Note that the story didn't start with Murdoch media outlets (to my knowledge); it was noted by multiple people on social media almost as soon as it happened and it went "viral" from there, so some people did feel it is a relevant topic.
If he is a legitimate reporter doing legitimate unbiased reporting, so be it. But ABC has plenty of resources reporting on the story, and him flying in and making sure his helicopter ride is recorded and put online only reinforces my suspicions of him as a reporter. My opinion; I am allowed to have it.