Now the Neo-Nazis are quoting from the Big Ass Newspaper of Things That Never Happened. It is not how government, or the world works.
First off, the federal government has no prisons in DC. DC real estate is expensive, and the federal government has no legal impediment to moving prisoners over state lines(unlike the states). To save money, there are no federal prisons in DC.
The way you release someone from prison is by getting a court order. First the pardon comes down, and then because there is nothing left to hold them in prison, a court order to release them is given. The court order is taking longer, because it is a huge number of people, and because what they have been pardoned for is a bit vague. The solution to that is found in court, not in a prison break using US Marshals.
Most importantly, it did not happen.