And it appears that they did not sell off all that amount that they moved to the exchanges; maybe they got some advice to store most of them, as there might be more to gain out of it than lose when the bitcoin price appreciates more than it has as of now. 

Check out this post. German government having second thoughts. they withdrew back 1915BTC from the total amount which they deposited initially to dump, the reason for the pull back is actually yet to be known for now.