Unfortunately, Harrelson cannot be disciplined by MLB because, as an employee of Comcast Sports, he is not under the control of MLB. Of course, Reinsdorf, who also had a talk with Harrelson, can exercise his "persuasive abilities" and get Comcast to do something if he wanted.
I happened to be watching that game live when Hawk's rant occurred. To say it was unprofessional was an understatement.