what was described is the mites that live in the food and more than likely these mites are not a danger to the roaches.
In fact, there is at least species of madagascar hissing roaches (and probably some other species as well) that have symbiotic relationship with a mite species that lives on the exoskeleton and only eats the detritus that is found on the larger arthropod's body. Kinda like cleaner shrimp. I have two species of madagascar hissers and one will have the mites and the other won't even if they inhabit the same bin.
What you really do not want to end up with is the mite that is probably a subspecies, if not the same species a varoa mite that is decimating bee colonies all over the country. These things attach themselves to the exoskelon of the insect and suck its juices . I had an infestation of these things on some crickets that came out of florida. They seemed to be most destructive to the smaller nymph crickets and in the worst cases would attach themselves all over the head of the cricket like multiple limpets making it impossible for the nymph to feed. Luckily I have a special microscope that I could use to get a close look. Indeed, they looked just like the pictures of the dreaded varoa mites and seeing what they were doing to the crickets, it was easy to see why they would be so destructive to the bee industry. I could not find refferences to this type of mite infesting domestic crickets prior to my observations. I understand that, through selective breeding, the Bee Industry is producing a strain of bees that have developed the behavior of mutually cleaning one another which allows those colonies to survive whereas those that do not have this behavior do not survive a varoa infestation.