They cannot be applied in the US. Obama signed a law into place in 2010 which prevents the enforcement of foreign libel cases in the US if they're incompatible with the legendary First Amendment. In this case, the Admin can sit safely.
He's Polish, so if he has any EU assets or visits Europe they can be at risk. Its not just him, however, its anyone who posts rumors who is EU based.
US 'freedom of speech' laws only applies to US citizens, if the EU can get you the US will comply with the treaties.
Looking like its true, therefore not a problem.