My answer is yes and no. Yes, it is okay to continue to let him do math without turning every bit of it into a handwriting exercise. Dictating, using math software on the computer or writing out only a select number of problems would all be possibilities. I personally do not think it is an option though to just say he's got handwriting issues, so forget about it because over the long term it would benefit him to get as close to being able to write out problems as possible for him. If he is interested in upper level mathematics he will have to have way to communicate his answers.
I don't think math is the place where his handwriting needs to be taught but handwriting does need to be dealt with. I'm not sure what he's done up until now, but it takes very regular, structured consistent practice to try to build and improve the efficiency of those neural pathways. It can be frustrating difficult work but in time it does make a difference. Also, we found working hard to work on the core and improve upper body and hand strength did as much for handwriting as handwriting specific exercises.
