This is what the NC Department of Veterans Affairs says
If an individual had five years of creditable military service as of August 12, 1989, all of their military retirement income is exempt from NC state taxes.
I do not know why 100% disability would change this if you meet the above requirements.
I found this website where it says you can get more information about VA benefits in NC.
https://www.military.com/benefits/veteran-state-benefits/north-carolina-state-veterans-benefits.html
https://ncadmin.nc.gov/about-doa/divisions/veterans-affairs
