---Snip---
That was a good move. Took them long enough, but still. Also, it says that they moved a large portion to the cold wallet. Why not all?
Maybe the El Salvador government has its own reasons for moving some of the Bitcoins to cold wallets, so it's actually not that important for everyone to explore because the most important thing in this case is about the courage of the El Salvador government which is still making Bitcoin as an important investment asset for their own country.
because if they will need some cash they then need to sweep whole thing
It could be that at this time they still don't need more cash so they only move part of the amount of Bitcoin they currently have. Or it could be that what was transferred was only limited to the investment profits they had gained so far through Bitcoin even though they still wanted to have more Bitcoin for the future of their country.