You could do 24 years in the NG and not be entitled to veterans benefits if you enlisted after you enlisted after Sept. 7, 1980, or entered active duty after Oct. 16, 1981 anyone who joined after these dates has to served 24 months consecutive active duty unless they were activated and deployed to a combat zone.
Walz appears to have joined before the 24 month rule was put in effect in 81 so that would explain how and why he is entitled to veterans benefits these time line is important