What, they never heard him sing before?

From Wiki:

Though never released as a single, [Slaves & Bulldozers] has been applauded for Chris Cornell's outstanding vocals on it. Producer Rick Rubin played the song for the former instrumentalist members of Rage Against the Machine, to showcase Cornell's strong vocal ability before he joined them to form Audioslave.

On a semi-related note, I was listening to a wicked Tom Morello solo and wondered why the Grammy's rarely reward individual instrumentalists. The always shitty Grammy Awards pick a Best Male and Female Vocal performance for various genres and they also have the vague Best Rock Instrumental Performance. How about separate awards for the guitarist, bassist, drummer, keyboardist, et al? I know the Grammy's are mostly about glorifying pop-centric front men/women -- maybe they can hand these awards out the night before, a la the Scientific and Technical Academy Awards.