I read in some article that TMZ had interviewed him and he said the dates that Idol wanted him for collided with important dates at the school where he teaches, and he did not want to break those commitments, so he declined to do the show.
Here is his band.
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“You’re so hard on yourself. Take a moment. Sit back. Marvel at your life: at the grief that softened you, at the heartache that widened you, at the suffering that strengthened you. Despite everything, you still grow. Be proud of this.”