Enoch did not keep silent about the sin around him. Jude says Enoch prophesied about those evil people:
Enoch walked faithfully with God; then he was no more, because God took him away.
“As it was in the days of Noah,
so shall it be at the coming
of the Son of Man…”
Jesus Christ, Matthew 24:37
Enoch was a loyal follower of God. He told the truth despite opposition and ridicule.
So why is it not in the Bible?