Because it was tied in the shape of a noose. I saw the picture on your link, it’s a noose. Nobody ties a hangman’s knot at the end of a rope because they need to grab the rope, they tie it because they want the rope to look like a noose.
The only actual fact that has changed is that this particular noose was not tied to intimidate this particular black man. Was it tied to intimidate a different black man, all black men, or tied as an unthinking goof? When I was a kid I tied nooses all the time as unthinking goofs, literal gallows humor, with zero appreciation for the racial history.
So, the crew member who reported it was absolutely right to report it. HE didn’t know when the noose was tied, how the fuck could he? All he knew, all he reported, was a noose found in the garage of a black NASCAR driver.