Actually the whole idea of the GLUT machine (dubbed the 'blockhead' in Braddon-Mitchell's and Jackson's book, The Philosophy of Mind and Cognition) IS precisely to use live intelligent humans to store an intelligent response to every response a judge might make under a pre-specified limit (including silence and looping, which is discussed explicitly in the paper). The idea is to show that even though the resulting machine has the capacity to emit an intelligent response to any comment within the finite specified limits, it nonetheless has the intelligence of a juke-box. The point is that the intelligent programmers anticipate anything that the "judge" could say in the finite span. The upshot is that the capacity of a machine to pass a Turing Test of a finite length does not entail actual intelligence.
There is an aspect of the construction that you are not quite taking in. The programmers give a response to EVERY sequence of letters and spaces that a judge COULD type in the remaining segment of the original hour. One or more of those sequences will be a description of a laser, another will be a description of some similar device that goes counter to physical law, etc. The programmers are supposed to respond to each string as an intelligent person would respond. Here is the relevant part of the description: "Suppose the interrogator goes first, typing in one of A1...An. The programmers produce one sensible response to each of these sentences, B1...Bn. For each of B1...Bn, the interrogator can make various replies [every possible reply of all lengths up to the remaining time], so many branches will sprout below each of the Bi. Again, for each of these replies, the programmers produce one sensible response, and so on." The general point is that there is no need for the programmers to "think of" every theory: that is accomplished by exhaustion. Of course the machine is impossible but that is OK because the point is a conceptual one: having the capacity to respond intelligently for any stipulated finite period (as in the Turing Test) is not conceptually sufficient for genuine intelligence.