The US government can not censor speech for private citizens except in extremely limited terms.
This is a government employee communicating on behalf of the government. The government has every right to censor the speech that it puts out.
Also, for what it's worth, the US has much stronger free speech protections than the EU. Whether or not that's a good thing is up for debate.
A government employee will be censored for the speech that that employee puts out, full stop.
Same way as if that employee put out a hate filled speech about gay people.