YC appears to be interested in 1) new technology that 2) is valuable (something people want), with 3) unicorn potential (value in billions) and 4) founders that

YC appears to be interested in 1) new technology that 2) is valuable (something people want), with 3) unicorn potential (value in billions) and 4) founders that can devote >80 hrs a week getting it there before someone else does. If you fit this model, I don't see why age would matter. FTR, 4) tends to eliminate people over ~30. Also, my observation is that 1) favors the young who seem to have time to identify and play around with new tech in a way that older people typically do not, which would explain the median age of YC applicants, but not necessarily exclude applicants by age.