[smurph]

They don't say anything is illegal, they say it is 'prohibited'. They don't say who it is prohibited by, and since it's clearly not the federal government you have to assume it's just prohibited by the NFL itself. Of course nobody has to listen to a goddamn thing the NFL says, so why include the message? It's likely a CYA thing on their part, since it gives them the power to essentially disown any event or analysis that is related to their broadcast. Also worth noting is how the NFL is obsessed with law enforcement culture. Lots of the league employees are former police and FBI, so there is a good chance they actually think they have some kind of authority over what a person does or says in relation to the NFL.