Im near the same level of dyslexia as your husband. The reason he code like a mad man but cant type(words) for crap is because we are able to visually see how the code works in our heads. This visualization is where we excel when compared to normal people. Since Im able to see how the code is being run in my head my hands amazingly reacts with the correct code with out me thinking much on the code but more on the how the code is working. It's pretty cool how the whole process works. And this seems to work jsut as equally when reading code (with a few exceptions depending on how complex the algorithms are).
Just dont ask us to fully document what the program does. It can be done to an extent but it requires lots of advil and plenty of naps. (I get very dissoriented when writing and very tired too)