Sounds like a pitch to fill open positions at YC funded companies. Nothing wrong with it, just the verbiage of the post -- "surprising hack". It is a hack which feels like Sam just thought up of or made it up. Because otherwise, there is no need to correlate working for YC as a hack to get into YC.

There were other "surprising hacks" always mentioned here, have a solid product with good group, have a product which makes money, get a recommendation from other YC alumni etc.

This, this just sounds like, "hey, we want you to work for our companies. In case you ever want to start one, we will look at your app favorably then."