Theoretically, if Bitcoin was used, it could have been more transparent if they were required to report all the addresses and amounts used, but it would come with a risk of hacking or false hacking. Governments are pretty bad with cyber security, their servers get hacked quite often, now imagine if they used Bitcoin and their not only data, but their funds were also stolen. Another problem is that corrupt government officials could steal the coins and then claim it was a hack. In either scenario, there's zero chance of retrieving coins.