I don't think it's realistic to expect an RCT for this. Usually RCT setup for nutritional studies means "locking" people up and controlling every bite of food. However since the study in the article examines cancer risk (i.e. long-term outcome), doing an RCT with the idea of measuring who got cancer and who didn't would mean locking people up for years if not decades, which nobody would agree to.
that doesn't mean that the study is to be trusted 100%, just that it's not always appropriate to say "BS, need RCT", since sometimes studies like that aren't realistic
that doesn't mean that the study is to be trusted 100%, just that it's not always appropriate to say "BS, need RCT", since sometimes studies like that aren't realistic