Keynesian economic theory is to economics as elecrticity is to a computer, it only provides the general way in which it functions. Generally speaking, Keynesian economics is right about the way the economy functions, however the economy is full of exceptions, including, but not limited to environment, government, people, labor, society and more. The economy is not as simple as money, however, that is about as far as Keynesian economics goes in describing the economy. It is however, generally right. The resulting rise in the stock market is indeed because Keynesian economics do work.
Keynesian economics is only part of a large picture. After every crash so far there is a gradual inclination for the market to improve interspersed by abrupt peaks and valleys that are not always easy to analyze or interpret. Keynesian theory does help stabilize and smooth out the peaks and valleys but the economy will eventually end up where it is going regardless.