How much of it is true is a story for another time; the point is that it was funny and scathing (scathingly funny? For ease of reference, I’ll refer to his original now-cached version as V.1 and the replacement apology/explanation as V.2.
But, under 32 USC § 109(e) "A person may not become a member of a defense force if he is a member of a reserve component of the armed forces." However, if an Officer or Soldier is placed on the retired roll of the Active Army or Reserve components, he or she is eligible, with prior approval from the Governor, to transfer their commission to a military command within that State, and continue to serve at present or higher rank.