Making some star cutoffs score-based and others leaderboard-based would make things more complicated than they need to be. They shouldn't lower the gold star cutoff for Cult of Personality just because it's a hard song. If a few songs out of nearly 4,000 are impossible, so be it. Some songs are impossible to gold star in the main Rock Band games.
Yeah, they fixed the threshold back in RB1 because some songs COULDN'T be Gold Starred, not because you weren't good enough to FC a long solo. Your playing ability doesn't make anything broken.
Witticus: "GeeNef speaks to me like schizophrenia, his words touch me where my priest could reach."
In a similar vein, it's pretty silly to say that (as one example) Welcome Home should be much more difficult to Gold Star than other songs of similar technical difficulty simply because there are only five vocal notes in the first checkpoint. If there is a way to avert this inconsistency, it should be done.