Perhaps he should have read the bible, it says right there that no man knows when Jesus will return.
When you start reading how Camping came up with the date, you realize very quickly that he is interpreting Genesis 5 (the “begats”) in a way that NO ONE else did. Where is says “Seth lived 130 years and begat Enosh and then he lived 807 years after”, Camping takes it to mean that Enosh was born when Seth was 937 years old. Again NOBODY interprets it that way except Camping.