[donking]

I've seen players do this quite a bit. Ususally they are weak/bad and think it helps as a way to "limit the down side." I've seen these same players make 3 or 4 short-buys and then leave to another table after having "bad luck."

I think your prop/dealer is different though. Seems that he does not want to kill a table by being seen as good/chip leader. It may scare-off some players be seeing him with a large stack.