The idea goes like this: What is, actually, special about humans? There is a lot of possible answers you could give here, depending on which reference class you compare them to. You could compare them to the other races of the galaxy, and say they have exceptionally high endurance (though of course less than those designed to be better, like Orks and Necrons). You could compare them to the native of their home world, be it holy terra or dath ilan, and claim the most important trait is their intelligence, or tool use. If you were to ask someone from the imperium, they might reply their faith in the god emperor, but that's not really a useful answer outside of a handful of contexts.There's also the implicit bias included in the word special, although the baseline equivalent used here doesn't match it, that acts as a soft delineation on what kinds of traits would qualify as a possible answer.
A less literal but more accurate translation of the idea, then would be "Why is it that humans reaching out with alternatephysics abilities are be taken over and altered by infohazardous entities, possibly from some location known as the warp? The best guess dath ilan has is, after checking to try and be sure the answer isn't that other people or animals aren't being so attacked, is that this alternatephysics has both economicmagic and conceptualmagic, and the actions taken opened some kind of conceptualmagic weakness in those doing the contacting. Such a setup is rather disdained by traditional dath ilani alternatephysics worldbuilding, but there isn't really any reason that reality has to follow those, much less a reality as far down the probability distribution of possible worlds as this one is. As such, what they're trying now is to include as many mundane conceptual barriers as they can without interfering with the actual translation. Other experiments have shown it entirely possible to use the alternatephysics abilities to operate communication infrastructure like cell phones, even in the absence of any carrier service. When testing control groups, it worked even when the cell phone had critical parts swapped out for broken ones, or even outright missing, although with more difficulty. The setup they're using now has an economagic user operating a secured keeper radio device, with the outputs reworked into texr transcription. Nearby it are prisoner restraints, locks, physical printouts of codes for security programs, not because they're expected to be useful but because dath ilan doesn't believe in testing only one variable in a n experiment when starting from a state of maximal confusion. It's hard to deceive a keeper, but there are ways, and this one has been convinced that this methodology has been tried before and that their alternatephysics model suggests it's secure. Several of the more popular methods of communications shielding from dath ilani conceptualmagics media are also included, though to an earthling most would seem totally nonsenical; the most clearly identifiable instance is a scale model of security made from specially treated materials, and even that doesn't align precisely with how it would be expected to function.