"Stupidly"?

I was astounded when I heard that some people were criticizing President Obama for saying "stupidly" to describe how police officers acted when arresting a black man, who was supposedly breaking into his OWN home, even though he showed proof that he lived there!
I looked up the word to make sure that I wasn't mistaken, and I wasn't. You wouldn't say, "they acted stupid." That even sounds incorrect (at least to intelligent beings)! The President said it correctly, "they acted stupidly."
All I am going to say now is, look it up!