The most important thing for any institutional guy is not just price levels but liquidity. If he is buying then he wants sellers i.e liquidity at a certain level. Now unfortunately this happens to be the place around certain supports where retails place their stops. These stops create liquidity for the Institutional guy. This is the most likely place he can get a fill for his orders. So he is more likely to place his buy bids below support in the hope that market will drift down, hit a few stops and create liquidity for him.
Anyways.. all of this talk doesnt make any sense to me. A stop hit is a stop hit. Doesnt matter who hit it and for what reason.