El Salvador probably wanted to keep their image as a bitcoin friendly country. Not only do they want to appear friendly to bitcoin, it seems like they want to be a country known for having a lot of bitcoin and possibly get investors in their country. I have seen some people doubt IMF's reports but what do you think? It makes sense if bitcoin has become El Salvador's political move.
The IMF is afraid of Bitcoin in the sense that they don't have confidence in El Salvador Bitcoin reserves and since El Salvador want loan to grow their economy, they don't have choice but to make amends to what IMF instructed them. If they don't, they wouldn't have any laon and without loan, the country will remain backward and there is not independent organizations that is going to lend El Salvador that amount of money, even if there is the are going to ask the same condition.
Do I blame them? No! Do they alternative? I am not sure there is any and neither can the country survive without any loan. They need that money to grow their economy. They can't sell the Bitcoin because they have come far, they have gotten good recognition with Bitcoin, if they sell it now that means it might take ages before we see that country on the news again. They have to just accept the terms and get the loan or get the loan and come back to Bitcoin but there is a penalty fine if you breach in the loan contract.