There is some dispute about that.
Trump has reportedly used that mannerism to mock multiple reporters.
It's about being "flustered", not "autistic".
Of course Trump was making fun of the reporter.
Let's not have blinders on like Hillary's supporters do. I'll be voting for Trump because there is nothing in Heaven or Earth that would make me vote for the Hildebeast.
But Trump is far from the perfect candidate. He has said and done many things (this incident, saying McCain was not a war hero) that would probably give me good cause to vote for someone else in any other year.