Commissioned Officers retire as early as 40-42. I think there is
a saturation of ranks at MAJs and LTCs. They have to make way for
younger officers and therefore have to be retired.
I too don't see a logic for Commissioned Officers to serve to 50
years old. After NSF, they would finish the same 10 years cycle at
about the same time as everyone else. And if everything is smooth,
one should MR before 35 years old. So, whether it is NS to 40 or 50
years of age does not appear to be relevant.