It is rude to make jokes about other people
Don is running for election and making a speech to potential voters.
Don wants to feel good about himself.
Don talks about real issues and how he will help people in their lives.
Don makes fun of a disabled veteran on stage waving his hands and stumbling mimicing him.
Many potential voters respect Don and vote for him.
Many potential voters get turned off and resent Don and don't vote for him.