No, it isn't funny.
Being a ditz is funny.
Being a cripple is not funny.
Making a social gaffe because you were unaware of a cripple being a cripple is also not funny.
Use your imagination and construct a funny parody of this for SNL and you will seewhy this was not done. There is no way to make it funny. You are being cruel to two people at once.
On the other hand, making fun of some ditz who says she knows all about foreign policy (despite getting her first passport after living in a noncontiguous part of the US for 44 years) because one tiny insignificant Alaskan island is near another tiny isolated insignificant Russian island IS the sort of thing a satirical skit was made for.
I bet Sarah Palin knows more about Santa Claus 'cause she lives so close to the North Pole. I bet she has close personal friends named Dasher, Dancer, Prancer and Vixen. I bet she's met Rudolph.