That is odd? Is this a new feature? 1 time I had a motocycle accident and was in hospital for a week. I was absent from the game and yet when I relog back in after 10days I was still in the clan.

Trainees get auto kicked  if you worm or higher u do not 

Greetings. Unfortunately, we are not planning to change this game feature, because we strive to keep your Academies as clean as possible. You may change the rank of players which show good results, so they won't be kicked.