I'm not sure it was as obvious as it's being made out after the fact. It took 12 of them -- TWELVE -- to determine this was a door pull fashioned in a weird manner. That many FBI aren't assigned to murder cases.
At any rate, I'm not sure why folks are still flipping out about this. Crew member spotted this and reported it. NASCAR and apparently half of the Alabama FBI outpost (well maybe that isn't so surprising) investigated and said, 'yep, noose door pull - been there for a year tho,' and determined this wasn't a fresh hate crime/something targeted at Bubba. It should be over and done with and most should be fairly happy with the outcome given that it appears to have been an odd misunderstanding rather than a targeted crime but people want it to be more than that. Bubba's gotta be either 'the lying minority' or the 'the targeted victim.' It can't be what the FBI determined -- weird stuff but old weird stuff and therefore not a targetted crime -- there's gotta be an angle for folks to play.