"Since “righteous” means to be without sin, that goes against the Bible,"
The word actually has a dozen or more meanings. You carry on about one meaning. You complain about someone putting words in your mouth but that is exactly what you did to the author. When he referred to the number of "righteous" in America, he was WAS NOT using your chosen meaning above. And it's obvious (except to you) which meaning(s) of the word he was using.
This is not Bible Science.
I see only one general meaning for the Hebrew word “tsadaqah” and its derivatives, e.g. “tsaddiq”. Same applies to Greek cognate “dikaiosyne”. If you care to list the other meanings you refer to, please do so, but make sure you refer to the Biblical text.
Hebrews 12:1 warns us about “the sin which doth so easily beset us”, furthermore.