For somebody who is already enjoying a good form in test cricket, IPL is always a threat as the mindset needed to succeed in T20 is far different than in Tests. I would say Harris had made the right and brave decision to ignore the money that comes with IPL to focus on his country's interests. 99.9% of the Indian Players wouldn't have done that.
But for somebody who suffers from lack of form IPL could be a boost as there is a chance to experiment in short spells in varying playing conditions. Mitchel Johnson did benefit from IPL after the poor test series against India. With so many people vying for a spot, Harris decision is not going hamper IPL. But Australia will most definitely benefit.
