Just because you have the right to free speech doesn't mean you have the right to be free from criticism. And when you're the mouthpiece for a company, business or party... it is understandable that they wouldn't want you tarnishing their image.
"There is nothing which I dread so much as a division of the republic into two great parties, each arranged under its leader, and concerting measures in opposition to each other. This, in my humble apprehension, it to be dreaded as the greatest political evil under our Constitution." óJohn Adams