That's assuming they're actually a thousand years old though. Which calendar are they using for reference? They could be sunk in to an area of space where a hundred years to them is what we'd consider a year much like how the Wine in Suramar ages faster in storage relative to the space around it.
Your body will still naturally age but the way you perceive time could dramatically shift. I'm not exactly sure how long they were gone for but Turalyon looks about as old as we would expect him to be.