The economic stimulus in 2009 rightfully grows the US government by keeping it's economy strong. The stimulus allows for new job creation, as well as the flexibility for both businesses and consumers to continue spending. This helps the economy gain strength during a recession/depression.
When the economy is strong, the country is strong. The unemployment numbers decrease, the strength of the US dollar rises, and the stock market continues to grow.
The stimulus does not rightly grow the government because it does not grow the government at all. The stimulus money is taking money from the government and giving it back to the people. On the surface this seems like a good idea. The problem with that line of thinking though is that it forgets that we already have a huge national debt and cannot afford to give back the money.