I just discovered this Examiner Article from 4 months ago, 'Podesta Group Launching Investigation of Trump'. John Podesta was concurrently working with his Center for American Progress Action to fund the 'Trump Investigative Fund'. This is an effort to

"hold Trump accountable to every promise, relentlessly track and expose his conflicts of interest, and expose the records and values of the people he is selecting to run the country"

Here are the results of his efforts:

https://www.resistance365.com/about

https://www.project1461.org

https://thinkprogress.org/the-trump-investigative-fund

It seems clear to me now why JP would get the columnist position at The Washington Post. If all his future articles are going to be criticisms of how Trump isn't fulfilling his promises, then the trajectory is clear, be a roadblock and get in the way of progress. Do it with as much force and hit him from as many angles as possible until the message hits home: This President has got to leave before he comes looking for us. It's silly that this kind of destabilization of our country is allowed under the protection of First Amendment.