The rejection of Bitcoin by the IMF does not have a direct consequence for Bitcoin users, but it may make it harder for Bitcoin to be accepted in international financial systems. This could limit the use of Bitcoin and have negative consequences, such as other countries banning or regulating Bitcoin.
Unless IMF starts some sort of "sanction" on countries that have adopted bitcoin (stuff like rejecting loans and putting pressure on them like that), I don't see how publishing an "opinion" about bitcoin can have any kind of consequences in countries and their adoption of bitcoin.Bitcoin will have no effect on adoption even if the IMF does not support it and has hinted to discourage the use of bitcoin globally.
However, there are countries whose economies depend on the loans given by IMF and I live in one such country. IMF will impose restrictions never to legalize bitcoin until our government pays off all the loans. It's difficult for an underdeveloped country to pay off all the loans and this means that our dream to legalize bitcoin in our country seems far away.
