They believe that through this, they are reducing the risks of losing all their bitcoin should quantum threats be real in the future and their holdings get attacked. That is the only reason why El Salvador is moving their bitcoins and I believe this should be something we can all learn from El Salvador. Distributing your bitcoins in more than one wallets will save you in the future and El Salvador knows this.
There can be been changes within the government team. The person behind Bitcoin and El Salvador maybe have mire personnel changes, and these have included important person who even knew the private keys. So this security act could be also an important move for the hole organization. People are predictable, and everyone has his price. For someone its money, for other loyalty.