This may perhaps be more obvious to a naturalistic philosopher or natural scientist, than a computer "scientist" (ie., a mathematician).
The meaning of the term "pen" in "pass me that pen" includes the pen. So when this room is asked, "pass me the pen" and it replies "i cannot pass the pen" (or whatever it replies) -- it should be obvious that the person in the room, or any function of their activity, has never acquired any reference to "the pen". It is wholly unaware that there is a pen at all.
The purpose of this thought experiment is to show that syntactical correctness or apparent "arrangement of symbols in 'a' correct order" is radically insufficient to evidence semantic competence.
This, again is perhaps more obvious to scientists -- the symbol order is only a proxy measure of semantic competence in people. It's trivial to come up with processes which clearly lack the capacity for such competence and yet are measured (/observed) to produce symbols in the right order.
In many ways, it's an over-engineered thought experiment. However I'd say Searle was baffled that more obvious phrasings of the problem seemed to confuse others, ie., that an observation of symbols isnt an observation of meanings -- one isn't a reliable measure of the other. Only under very many additional conditions does such a relationship hold in people.
Turing was not interested in producing systems that had such competence, so he may well agree with Searle in some ways at least. However, many students of computer science receive no empirical education whatsoever, and lack the basic vocabulary and understanding of the nature of the problem of meaning.
Eg., that in order to mean "pass me the pen" one must be able to acquire a reference to "the pen" which any system unable to observe its environment at the very least cannot do.
Turing machines lack devices, and hence lack any capacity to in principle refer to objects in the world. The only thing a turing machine can be said to do is express an abstraction ( a function of nat -> nat) -- since it is an abstraction.
No capacities follow from expressing such a computational abstraction -- Searle thought the chinese room made this obvious to those who didnt find it so. But he was baffled that anyone didnt already find it obvious.
One could make the same point with physics, rather than with meaning. Eg., the earth orbiting the sun computes +1,-1,+1,-1 .. and so does an infinte numer of physical processes that share no properties with the earth, or the sun, etc. Thus just because we observe +1,-1,+1... does not mean that "inside the chinese physics room" there's an earth orbiting the sun. It could literally be anything.