I don't know if it's standard, but at every job I've had, I've had to sign a form stating if I made derogatory comments about my employer in public (or on social media), or if I made public statements that could portry my company in a bad light (ie, if I made racist comments while somehow associating myself with a company, like wearing their jacket or something), I could be reprimanded or fired. And I'm talking about pretty small-time jobs: Blockbuster, a lab tech at a civil engineering firm, and a hotel front desk agent. I imagine someone who, as has been mentioned, has his name plastered along side someone like Dior's...
Well he probably had to sign a much more in-depth version of that form.