Oh, good grief. It's the oldest rule in the book (rule 42, I believe) - if you are on concessionary travel, you wind your neck in and behave. You are not a "normal passenger". yOU HAVEN'T PAID. (Oops hit caps lock. Still, quite effective).
If you work for Ford, you probably don't park a Toyota in the car park. If you work for Next, you don't turn up to work in an FCUK top. If you know what shares in your company are going to do tomorrow, you don't talk to your friend the journalist.
No, you are not free to do what you want. You are accountable.