In a way he is right, in many essays I tend to be sympathetic towards a Keynesian / interventionist viewpoint. When teaching A Level economics we discuss different models of the economy. In particular we show the Keyensian vs Monetarist view of the Long Run Aggregate Supply. This is very simplified view
Keynesian view of Long Run Aggregate Supply
The Keynesian view is that output can be below full capacity for a long time. In a recession, labour markets don't clear and we are left with demand deficient unemployment. Keynes' general theory of money was written in the 1930s, when there was ample evidence of the failing of the free market to achieve full employment. Faced with this mass unemployment, Keynes advocated government intervention (higher government spending) to stimulate a depressed economy.
Monetarist View of Long Run Aggregate Supply
The monetarist view is a development of the classical theory. To simplify the model, Monetarists believe the Long Run Aggregate Supply Curve is inelastic. If AD rises faster than long run aggregate supply, there may be a temporary rise in real output, but, in the long run, output will return to the previous level of Real GDP. The impact of this theory is that government attempts to influence Real GDP through fiscal policy are at best ineffectual. This is because Expansionary fiscal policy only causes inflation. Classical economists argue that the economy will return to full employment, presuming that obstacles to the free working of markets are removed. inflationary pressures.
Sometimes when teaching a student will ask me - Are you a Keynesian Sir?
I am reluctant to say yes, because I feel that a good economist should not be tied to a particular ideological viewpoint. A good economist should always be flexible, ready to criticise his own belief's if evidence points in other directions.
However, broadly speaking, I do believe that governments or Central Banks should attempt to stabilise the economy through monetary and fiscal policy. They should not aim to avoid every cyclical fluctuation. But, intelligent monetary and fiscal policy can avoid the worst excesses of boom and bust. In a recession, fiscal policy can play a role in shortening the duration and intensity of the recession.