One possible explanation ....
This rope had been replaced and somehow left in the corner. Some mechanic who knew what it was found it and went to throw it out and held it up for someone else, perhaps visitor or something, and said "Hey, look, a noose!" as a joke. That neophyte reported it to the President of NASCAR who now felt he had to take action. The original mechanic tried to explain, was forced to retrieve the noose from the trash, and now the word had spread.
So, they call the FBI, who sends agents who talk to everyone, see the "noose" and fairly quickly write it up trying to limit the damage to all parties. Henceforth, all garage door pulls use handles instead of the simple knot.
It is one possibility, an example of how something gets out of hand quickly in this environment. As to why Wallace wants to maintain this is a real noose, well, you can draw your own conclusions.