Also, from the side, it's in no respect clear that "information" is itself material. If what's powering the objection is the intuition that "information" doesn't look like things, one will still want to know how the information is in our minds qua information. A certain computational view wherein a certain materialist view of the computer is supposed is, I think, being smuggled in the back door to power the objections intuitions.

The argument is from De Anima III.4:

Therefore, since everything is a possible object of thought, mind in order, as Anaxagoras says, to dominate, that is, to know, must be pure from all admixture; for the co-presence of what is alien to its nature is a hindrance and a block: it follows that it too, like the sensitive part, can have no nature of its own, other than that of having a certain capacity. Thus that in the soul which is called mind (by mind I mean that whereby the soul thinks and judges) is, before it thinks, not actually any real thing. For this reason it cannot reasonably be regarded as blended with the body: if so, it would acquire some quality, e.g. warmth or cold, or even have an organ like the sensitive faculty: as it is, it has none. It was a good idea to call the soul 'the place of forms', though (1) this description holds only of the intellective soul, and (2) even this is the forms only potentially, not actually.

Aquinas comments:

680. The following argument may make this point clear. Anything that is in potency with respect to an object, and able to receive it into itself, is, as such, without that object; thus the pupil of the eye, being potential to colours and able to receive them, is itself colourless. But our intellect is so related to the objects it understands that it is in potency with respect to them, and capable of being affected by them (as sense is related to sensible objects). Therefore it must itself lack all those things which of its nature it understands. Since then it naturally understands all sensible and bodily things, it must be lacking in every bodily nature; just as the sense of sight, being able to know colour, lacks all colour. If sight itself had any particular colour, this colour would prevent it from seeing other colours, just as the tongue of a feverish man, being coated with a bitter moisture, cannot taste anything sweet. In the same way then, if the intellect were restricted to any particular nature, this connatural restriction would prevent it from knowing other natures. Hence he says: ‘What appeared inwardly would prevent and impede’ (its knowledge of) ‘what was without’; i.e. it would get in the way of the intellect, and veil it so to say, and prevent it from inspecting other things. He calls ‘the inwardly appearing’ whatever might be supposed to be intrinsic and co-natural to the intellect and which, so long as it ‘appeared’ therein would necessarily prevent the understanding of anything else; rather as we might say that the bitter moisture was an ‘inwardly appearing’ factor in a fevered tongue.

681. From this he concludes, not that in fact the nature of the intellect is ‘not one’, i.e. that it has no definite nature at all; but that its nature is simply to be open to all things; and that it is so inasmuch as it is capable of knowing, not (like sight or hearing) merely one ‘particular class of sensible objects, nor even all sensible accidents and qualities (whether these be common or proper sense-objects) but quite generally the whole of sensible nature; Therefore, just as the faculty of sight is by nature free from one class of sensible objects, so must the intellect be entirely free from all sensible natures.

There is talk here of the forms the intellect takes on, of the natures of what the intellect takes on, of the objects of the senses and the intellect, and of the things to which the senses and intellect are open. It's my suspicion that some of these terms are used loosely by bother Aristotle and Aquinas.

Aristotle thinks that there are both common and proper (or "special") sensibles. Common include shape, size, and movement; they are common because they can be detected by more than one sense. The special sensibles are the proper objects of the individual senses: color, sound, odor. Identified as such, they stand to any particular object of those senses as determinable to determined. So if I see that something is red, I see that it is a red sensible, and red is something determined of the determinable color.

The idea here is that if, in perception, a particular sense has a determinable special object, then, prior to perception, the organ of that sense cannot already be determined to anything to which that object is determinable. The pupil must be clear if it is to be open to receiving both red and blue.

The Aristotelian argument, then, is is this. The intellect can think about all bodily things. But if the intellect has a bodily organ, then it has some bodily nature, and if it has some bodily nature, then it is unable to think about bodily things of that nature (or of any contrary determinations of the same determinable). Thus, the intellect lacks a bodily organ.

I am not exactly convinced of the soundness of this argument. I am inclined to say that, if it is sound, then the intellect cannot know itself except negatively. It can recognize that "its nature is simply to be open to all things," but I think this cannot really be its nature, ontologically speaking, because then, for us to recognize that, our intellects would have in some sense to take on that nature, and that is supposed to be impossible. Perhaps one could say that being open to all things is proper to its nature, but humans cannot know its true nature. In that case, though, it would have to be being open to almost all things that is proper to its nature.

Generally someone who wants to defend this argument has to provide a clear account of what is meant by "sensibles," "natures," "forms," etc. here. As the sense examples suggest, what I think we are really interested in are something lie formalities under which objects are seen, heard, known, etc.