I've never liked George Osborne (I think he is a slimy rat) and this faux pas, here on his part makes him even less endearing. I think Nick Hornby's comment in the last paragraph sums it up nicely:
Writer Nick Hornby, whose 13-year-old son Danny has autism, and who helped co-found TreeHouse, an educational charity for children with autism, said: "George Osborne doesn't seem to have noticed that most people over the age of eight no longer use serious and distressing disabilities as a way of taunting people."