In general, there is nothing wrong with the government legislating what its employees may say when acting as agents of the government, just as there is nothing wrong with a corporation telling its employees what they may say when acting as agents of the corporation. Free speech does not mean, "Your employer cannot fire you for publicly contradicting company policy while on the clock." Note that there are limits to what the government can mandate with regard to its employees' communications, and the Florida bill may run up against them.