How or why do arahants not experience aging & death? There are various verses in the Pali suttta that give the impression arahants not experience aging &amp; death, as follows:


  Then, monks, being subject myself to aging... death... seeking the aging-less, deathless... unexcelled rest from the yoke, Unbinding, I
  reached the aging-less... deathless... unexcelled rest from the yoke:
  Unbinding. MN 26
  
  
  
  A sage at peace is not born, does not age, does not die, is unagitated, and is free from longing. He has nothing whereby he would
  be born. Not being born, will he age? Not aging, will he die? Not
  dying, will he be agitated? Not being agitated, for what will he long?
  It was in reference to this that it was said, 'He has been stilled
  where the currents of construing do not flow. And when the currents of
  construing do not flow, he is said to be a sage at peace.' MN 140
  
  
  
  21. Heedfulness is the path to the Deathless. Heedlessness is the path to death. The heedful die not. The heedless are as if dead
  already. Dhammapada


How or why do arahants not experience aging &amp; death?
A sage at peace is not born, does not age, does not die, is unagitated, and is free from longing. He has nothing whereby he would be born. Not being born, will he age? Not aging, will he die? Not dying, will he be agitated? Not being agitated, for what will he long? It was in reference to this that it was said, 'He has been stilled where the currents of construing do not flow. And when the currents of construing do not flow, he is said to be a sage at peace.' MN 140


Here, I think the Buddha is telling that an arahant wouldn’t be born in future lives. Therefore, there will be no aging. When there is no birth and aging there will be no death.

Arahants don’t experience aging and death in this because they know that only their body is aging. Their body still age but they don’t assume the body to be “me” or “them” because they have cut off all fetters. 


  The sage at peace is not reborn, does not grow old, and does not die. They are not shaken, and do not yearn. For they have nothing which would cause them to be reborn. Not being reborn, how could they grow old? Not growing old, how could they die? Not dying, how could they be shaken? Not shaking, for what could they yearn? ‘They have four foundations, standing on which the streams of conceit don’t flow. And when the streams of conceit don’t flow, they’re called a sage at peace.’ That’s what I said, and this is why I said it. Mendicant, you should remember this brief analysis of the six elements.”
  https://suttacentral.net/mn140/en/sujato


Here, it said a sage is not reborn