Interest rates are an unreliable indicator of the stance of monetary policy. To quote Milton Friedman, "Low interest rates are generally a sign that money has been tight, as in Japan; high interest rates, that money has been easy." It is true that short-term interest rates can fall immediately after monetary easing occurs. (They always then rise, and if monetary policy stays loose nominal interest rates will rise to above where they were before the monetary easing occurred.) When interest rates do fall due to monetary easing, real interest rates always fall further than nominal interest rates do (since inflation expectations are rising); but from Jul 2008 - Nov 2008, real interest rates (as measured by TIPS yields) actually rose. TIPS spreads fell to negative levels in late 2008, forecasting substantial deflation (which has been borne out by changes in the overall price level over the last three years).
Furthermore, even when interest rates do fall in response to monetary easing (long-term rates rose on expectations of QE II), that effect only means interest rates fall relative to what they would be without the monetary easing. Interest rates still respond to the market factors that determine the supply of and demand for Treasuries. In the summer of 2008, the market interest rate, assuming a constant stance of monetary policy, on short-term Treasuries was falling, due to the financial crisis driving up demand for safe assets. The Fed kept that fall in interest rates from happening until October, which meant holding interest rates above where they would have been assuming constant monetary policy. That was an effective tightening of monetary policy.
