I am not making any accusations against anyone - it is obvious that Paul Graham has an age bias - he says so all over the place, but there is no law against having a bias. Age discrimination is almost impossible to prove, but if it is being used in the decisions of who gets into Y-Combinator someone should look into it.
See comment above. There was another interview or blog post where he talked about his preference for young people more extensively, but I can't find it. Do you happen to know how many people over 50 have been accepted into Y-Combinator?
Wake up. Discrimination is not cut and dry, law is not cut and dry, and reality is not cut and dry.