If I did that every day for eight hours a day, the risks that you cite would indeed be real and the indicated precautions would indeed be absolutely necessary.
I am a hobbyist. I have done this about half a dozen times in the last four years. I am not going to get a chronic disease from sandblasting for a grand total of about ten minutes in a year.
What you are suggesting is going waaaaaay overboard for my purposes.
I don't need to select a specific grit. The purpose of blasting in this application is twofold: to provide a surface that is free of corrosion, previously applied finishes, etc. and to rough up the surface for better adhesion of the chosen finish.
Given that the subject of discussion is coating, rather than bluing, I fail to see how grit selection is going to have much impact on the end results of applying a matte finish.
If it makes you feel better to use a different media, go for it. If one is a professional who does this sort of thing for a living, then your advice is particularly timely and important.
Any process, no matter how good, must match the intended end use for it to be relevant.