It's not appropriate for the official social media account of a government agency to tweet political content that criticizes the current President. That's going too far, and I'm not surprised at all that they were told to shut it.
It is fine for NPS to report occurrences. However, it was not fine for them to make a comparison of inaugurations.
The offices of the government should and always should remain neutral. They should be judged on doing their job properly. Should the EPA pretend to be Milo on how they think that Trump's/Rep party's ignorance on Global Warming is bad? No they should be advising us on upcoming, and current threads, showing superfund cleanup efforts, creating effective change, etc.
It's hard to judge an organization correctly when it's trying to play politics. When you're wrestling with a pig, you're going to both get dirty, but in the end the politican likes it.