User blog comment:Master Sima Yi/Assassinews 05-08-'14 – Assassin's Creed: Rogue announced/@comment-173.189.47.87-20141019002746/@comment-1153722-20141019133041

Ah Tabai would have been in his 70s when Achilles was recruited. Altaïr didn't seem to have that much trouble in his 60s. And even if Ah Tabai wasn't able to move about anymore like he did in his 50s, it wouldn't prevent him from tutoring Achilles. He wouldn't need to be a sparring partner to be his mentor.