Actually the 15% IS the combined federal and provincial tax rate of the first 500K of business income. When the shareholders take the remaining 85% out, they pay as much as 45% tax. That leaves they paying about the same tax as an employee who earned salary at the top rate.  If the company pays its 85% out to shareholders who are at a lower rate than 45% then the overall total tax could be less than a high rate employees tax.  So Wolfson's not totally wrong but he has chosen to use the most extreme example that basically NEVER happens in real life.  That's called SPIN and it's misleading and too important of an issue to let him get away with it. If it's not SPIN t it's ignorance or a case of academia not knowing reality.  And Trudeau and Morneau are listening to him. 
Income splitting is a fair target but the method drafted is horribly complicated and subjective. There are better ways. Instead of pushing the political agenda Wolfson,Trudeau and Morneau ..read my article from last week!