No this is an example of pointing out hypocrisy. He says that others should do what he is not willing to do. If he were to practice what he preached, the bottom 50% of income earners would have access to his beach.
Technically, there was no ad hominem fallacy. RcouF1uZ4gsC just argued that Khosla is a hypocrite.
Under a less charitable one, RcouF1uZ4gsC was discrediting the message by using the messenger's ``ethos''.