I could be wrong but personally I think someone probably reported some-other-site.rf.gd but google is nuts so it blacklists .rf.gd affecting all .rf.gd websites instead of blacklisting just the single bad site
One of the first things I do after installing a browser is disable the google safe browsing setting as I find it too annoying
There is a post about google safe browsing by Admin which will be more accurate than my thoughts