I wonder why the White House bothers to let Peter Doocy into the room.
The same reason Trump couldn’t ban Jim Acosta. The White House can set content-neutral criteria for which outlets or reporters are allowed to attend briefings (have to have an audience of a certain size, adhere to a dress code, refrain from grabbing your crotch and screaming at random intervals, etc.), but it can’t engage in viewpoint discrimination. No matter how stupid or toxic that viewpoint may be.