Considering the premise of the joke was based on the age old tactic used by Klansmen and other bigots to dehumanize black people by mocking their hair I'm gonna go with yes... it was racist. Cripes, it's a joke that would have been considered inappropriate 40+ years ago. The kind of joke you have to scold your racist grandpa for telling in front of the kids.
Do you find old Nazi propaganda posters where the artist intentionally exagerates Jewish noses funny/appropriate? Same general premise.
I also stated upthread that redneck jokes aren't appropriate here either.
If you need to denigrate an ethnic group to get a laugh you may not be as funny as you think. I mean go right ahead if you want to, that's your prerogative, but I will never not denounce racism when I see it... which is my prerogative.
Sorry, but we are NOT living in a "post racial" society like so many try to claim. Once the actual hate, violence and systemic oppression stops THEN maybe we can amiably poke fun at each other. Until then it's tone deaf and hurtful.
BTW, "rednecks" a) are not an ethnic group, b) have not experienced the same horrific and historical injustices as other groups (and many MANY times have been the oppressors of the people they want to "joke" about) and c) the jokes directed at rednecks are not nearly as hateful... mostly because rednecks (or people pretending to be rednecks for$$$) themselves are the ones making up the jokes.
It's called having a bit of awareness and empathy for what others have and continue to go through.
Peace.