First off, I'm not a fan of SNL. I feel the writing has gone WAYYYYY down hill over the last few years and outside of political humor, they're just not funny. Hence they stick to political humor.
Secondly, my biggest problem with this sketch is how geographically inaccurate it is. Union, KY in Boone County? That's not the ideal community to portray as poor, out of work coal miners. Union is just outside of Cincy and has probably many more jobs than say... Prestonsburg or Pikeville.
Thirdly, what's the joke? Trump's an imbecile? Appalachians are too stupid to support someone else? Because that's just what Appalachia needs, more people making fun of them.