The IMF is a centralized institution, so they are not going to support a decentralized network, they want financial activities to be under the control of a central authority, but since BTC can't be under the control of any authority, they are going to try and promote their cbdc over it and talk of regulations for crypto.
IMF is not a state, but rather a fund, as long as the parties inside the fund agree to the proposal of Bitcoin as its knowledge and the two lending parties agree, so there is no objection to that, but this fund is directed to the policies of capitalism, and therefore it is unlikely that it will predict Bitcoin unless countries adopt Bitcoin.
You do not have to think about it in terms of a centralized and decentralized currency, but rather there is a lot of openness to the use of bitcoin in international trade if the concept of globalization diminishes and many countries try to move away from the dollar.
On a related note, the probability that the IMF will provide loans in Bitcoin is higher than that Bitcoin will be accepted as legal tender in the United States of America.