Governments shouldn't use taxpayer's money to participate on a highly speculative and volatile market, that's like common sense.
2) He probably knows (please don't take me as a conspiracy theorist, I'm just trying to imagine) that someone is gonna start another bull run soon, 'cause El Salvador attracted the attention of many big crypto investors, so a confrontation between Bukele and them about this topic is not so unlikely.
I don't think he has any insider knowledge, he's just a president with too much power, and it's ironic because Bitcoin was created to resist this kind of power.