This is what the young man said, it isn't clear that he's mocking. He was young and immature as we all are at one point. We grow in our walk with God and this young man is no different. The young man could have actually been asking Jesus what he lacked. Its not clear. But what is clear is that those commandments are reiterated by Paul when teaching the greatest commandment in Romans chapter 13. And the apostles teach them throughout the NT
16 And, behold, one came and said unto him, Good Master, what good thing shall I do, that I may have eternal life? 17 And he said unto him, Why callest thou me good? there is none good but one, that is, God: but if thou wilt enter into life, keep the commandments. 18 He saith unto him, Which? Jesus said, Thou shalt do no murder, Thou shalt not commit adultery, Thou shalt not steal, Thou shalt not bear false witness, 19 Honour thy father and thy mother: and, Thou shalt love thy neighbour as thyself. 20 The young man saith unto him, All these things have I kept from my youth up: what lack I yet? 21 Jesus said unto him, If thou wilt be perfect, go and sell that thou hast, and give to the poor, and thou shalt have treasure in heaven: and come and follow me. 22 But when the young man heard that saying, he went away sorrowful: for he had great possessions.