That's like saying 'it's not possible for a person to pour water into a tub without the water level within the tub rising.' Does the tub leak? Is the drain closed? How quickly is the water evaporating? How quickly is the person pouring water into the tub? Depending on the answers to these questions, the water level in the tub can go down even as the person continues to add water to it.
This concept is not all that different from an economy, as it's a system with inputs and outputs just like any other. Economically speaking, expansion of the money supply without increased prices is possible so long as there are matching or overpowering deflationary pressures. Keep in mind that, as I said in the post that you quoted, prices would be higher than they otherwise would have been; IE: there would have been deflation if the printing had not happened, and therefore a zero rate of inflation was substituted for a negative rate of inflation. The effect of the expansionary monetary policy is still there, it's just hidden by other factors.
For example, think of a town containing 1000 people, all of whom are using a currency with a total money supply of $100,000. If 1000 more people join the community, no other currency is printed, and nothing else is changed, then the money will tend to increase in value as there are more people desiring to possess and use it, as well as a larger total economic output of the town. If the central bank of the town printed more money, they could compensate for this effect - expanding the money supply without increasing prices.
Likewise, consider an economy in which the price of everything or nearly everything is dependent upon the price of oil. If the price of oil is falling, then the prices of all other products which rely upon the price of oil for production, transport, energy, etc. will also fall. Again, in this case a central bank could expand a money supply during this period and still have the end result be lower prices or zero price change on those oil-related products if the deflationary pressure upon the economy of the declining price of oil is greater than the inflationary pressure of the expansionary monetary policy.
All of these examples are similar to the ones I offered in my previous post. The central bank is not the only factor in the market.