This is not true, while the US army is feigning for recruits they are not this desperate. There is a definite age cut off 39 for the Air Force and navy, 28 for the marine corp, and 31 for the army.
The only way to get this old in the military is to be already in it as an officer, NCO, or Warrant officer, and then simply stay, but even then you will be usually forced out at 60-65.