I know that there are already some relevant questions.

I am a physics professor and I do know that pressure is considered as an *intensive* property and the justification for this.

Nevertheless, I am puzzled about something I read from a book (Engineering Thermodynamics Michael Horsley, Chapman and Hall 1993).

The author has a progress type question:
"If I have some gas in a rigid container (...), is its pressure an intensive or extensive property?"

My quick answer was **intensive** based to the common "half the container" argument. The author's answer is (to my surprise): extensive.

Below is (in his own words) the justification:
"If (...) I let half the gas out of the cylinder, then the pressure inside the cylinder will certainly fall and the pressure of the released gas will also be quite different from its initial value. Thus the pressure is an **extensive** property."

What am I missing here?