He promised $30 USD to every citizen, so they just need a fixed amount (known since the beginning) of dollars to do that regardless of the current (or past) price of BTC.
So it doesn't matter if the price of Bitcoin is "high" or "low", he had already separated the amount required to give $30 USD to everyone.
He is doing it the right way: Transparently and in the open, announcing publicly their purchases.
To those saying: "He should've bought when the price was lower!".
They are wrong: The Government's duty is not to 'invest' in Bitcoin, it's NOT appropriate for them to speculate with Bitcoin, and certainly not for the short term. They can buy and Hodl for the long term on their treasury as a hedge against inflation and that would be responsible and appropriate.
So don't get your panties in a twist and support this financial revolution in every way you can!