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.