Ehh, I can't tell if calling them cornrows was actually intentional or just a misspeaking. I sometimes do stuff like that with words like "headband" instead of "bandannas" where what I'm describing is somewhat similar but obviously much different. Sometimes you can tell what something is but just call it by the wrong name because your brain is doing several things at once and slips. If it wasn't just a brain-fart, it's pretty weird, I agree.
Questioning where the hair style is in 2013 seems like standard Simmons shtick that could apply to any culture's hairstyle (whether that is African-American, punk, European, whatever). Saying dreads can get stinky could be seen as weird and could have some bad racial connections though.
And implying that Mormons are more ignorant or less understanding than other people is pretty hateful, I don't see the other side of that (and I'm an agnostic who is not affiliated with the LDS church at all if people couldn't guess).