I was watching MSNBC last night and they had someone on who said he wouldn't be surprised if Trump staged the entire thing.
He could have just not picked Acosta to take a question from but it seemed like he wanted to make a scene.
He then also verbally attacked the two black women reporters. He knew that the news about Sessions replacement wouldn't be taken well so, as usual, he tried to put other news out there hoping that the media would talk more about that.
When he took Acosta's press credentials away from him last night, he thought that would do the trick.