Rih wouldn't fit the vibe of Timber at all. Recently, Rihanna's voice has gotten some soul and that would have slowed down the tempo of Timber and taken away from the beat.
YAS PITBULL omg he completely just spilled the tea, Shaki/Rih is REAL This reminds me of when Eve accidentally confirmed Gwen's pregnancy a few months ago
Also I'm glad Timber ended up with Ke$ha, I like her voice on it so much + the good sis needed it.