I am sure the theory is because it has lowered the cost of hiring a new worker by ~2%. So if there are say 500 business planning on hiring 50 or more workers in the next few months these business will now hire 51 new workers. Meaning a creation of 500 new jobs, which will make such a big contribution to our unemployment situation.
Yeah, that will work, particularly since that 2% cost reduction is for one whole year only. They could have given businesses a tax incentive from a different bucket if this is what they really intended. (even though I realize they don't really keep the tax streams separate).