Donald Trump is the CEO of the USA.
All executive agencies operate at his discretion and all persons employed therein do as well.
Government agencies do not have freedom of expression as the 1st amendment applies to THE PEOPLE - not the government.
To think otherwise would be to think that the US Army is permitted to bear arms because of the 2nd Amendment. Nope - that applies to the people. The Army just...is the Army...
Censorship of US Government by the US Government is not a 1st amendment issue.