Stanford makes a bet that employment numbers will be up but he didn't bet that the number of employees making $15/hr or less will be up.  This will only occur if all employers in this range are able to pass through the higher costs to customers.

Maybe a higher minimum wage won't be the end of the world.  Some people will be ahead and some people will be unemployed but it's almost certain that employment won't increase due to an increase in the minimum wage.