The federal government lawyers have said in court that Elon Musk was not the leader of that organization. Therefore, the fact that he said he has departed from Washington would not affect that organization.
Of course we know that he was leading it, and the president has said as much, and the above claims are all being contested in court by quoting the president. But anyway, if you want the official answer, now you have it.
But the official answer also changes over time. Because if Musk was not the leader of that group, then many of the actions that he claimed to take and many of the actions that people attributed to him would now be actions of a private individual, which would expose him to massive civil liability. Therefore, we can be sure that the government's lawyers will continue to change their story about when and where and how he worked for the government.
There are other comments that already give practical ways to accomplish what you say is impossible.