During the election campaign, many anti-Trump foreign policy professionals and academics declared their opposition to Trump. That is unsurprisingly still being held against them :
Now, just days before Trump is sworn in as the nation’s 45th president, the letter signers fear they have been added to another document, this one private — a purported blacklist compiled by Trump’s political advisers.
If Trump’s team is blacklisting all the people that signed these letters, that is somewhat short-sighted on their part, but hardly unexpected. It had to be obvious that Trump and his advisers would hold a grudge against these people, so it can’t exactly come as a shock that they are now holding a grudge. Remember that these letters weren’t just a dry list of objections to specific policy statements, but almost always included very pointed attacks on Trump’s personal flaws. Trump’s opponents were within their rights to make those attacks, and most of them were accurate, but they had to know that Trump’s people weren’t going to forget about it later. It is probably the case that many of the letter-signers assumed Trump would lose in the primaries or in the general election, so they didn’t worry about being shut out of a Trump administration that they didn’t think would happen. I assumed  most of the people that declared Trump unfit for office would be unwilling to work for him, but even if they are willing they should have known that they wouldn’t be welcome. Dan Drezner makes  much the same point today:
For the love of God, people, what did you think was going to happen? Did you think that Donald Trump, of all people, would be the bigger man? Did you think that the foreign policy flunkies and D-listers who attached themselves to Trump during the campaign would now act like mature, responsible adults? Because if you did, maybe your threat assessment capabilities are not as good as you think — in which case Trump’s folks are pretty smart not to hire you.
If there’s a lesson in any of this, it is that professionals that want to serve in government should refrain from signing their names to denunciations of candidates unless they are prepared to be shut out from government positions as a result. That doesn’t mean that they can’t take sides in the primaries or the general election, but it does mean that they should stick to advocating for their preferred candidates rather than vainly trying to block one they don’t like.