From the rule book:
The sanctity of the legislative session is of the utmost
importance! Once it begins with the President drawing three
Policy cards, the members of the government should be silent
until a policy has been enacted; then they are free to share (or
lie about) the details of the session.
The government is only the President and Chancellor. This is also intimated in the rule book. Other players are free to talk. The point of the rule is to prevent plays like a fascist president communicating to Hitler as chancellor what card to pick, for example. If a fascist president drew two liberal and one fascist policy, and wanted to ensure a fascist policy, he could groan and say "no choice" while passing a liberal and fascist policy, thus telegraphing to Hitler as chancellor that the president is on his team when otherwise Hitler might not know that and enact the liberal policy to remain hidden.