If economic agents, consumers and firms, know that the central bank will react in this way to an oil shock, trying to stimulate income and employment, inflationary expectations will increase very rapidly, reducing expected real income and thereby nullifying the effects of the monetary expansion.
If the central bank persists in this policy, the only result will be a price-inflation spiral, with no positive impact on growth. If the economy embarks in such a path, bringing back inflation will require a substantial tightening of monetary policy that will produce a substantial output loss.