For instance, if you're the FAA, you should express opinions about airline operations, air safety, etc. That is your role. If you are the FDA, you should express opinions about food and drug safety. And in both those cases note that you are a regulator, and within your domain, it is your role to regulate the players.

If you are the White House, you are not a regulator of anything. It is fine to express your opinion. In fact the White House has a daily press briefing for specifically that purpose. It is fine to call out people with whom you disagree. Perfectly OK to call them dangerous charlatans and liars. It is not OK to censor their speech. It is not OK use the implicit coercive force of the executive branch to encourage third parties to censor them.

It's not hard to understand.