"Negative evidence" does not mean evidence that indicates something did not happen.A statement in a court case that "Elizabeth Jones never lived in Missouri" is not considered "negative evidence." A "negative" word in a statement (such as "never") does not make that statement negative evidence. In fact, this statement would actually be considered direct evidence that Elizabeth never lived in Missouri ("direct" because it explicitly states she never lived in Missouri).
"Negative evidence" does not mean evidence of a "negative" event (eg. a record that indicates your ancestor was an axe-murderer).
What Is Negative Evidence?
His failure to appear in these records would be "negative evidence" indicating he was not living in that county after 1842. The "negative" is not because he is "not" living...it's negative because he's not listed in records we would expect him to be listed in if he were living in the county, particularly when he was listed in those records before 1842.
His failure to be listed does not mean he's dead. He could simply have moved. One needs to be careful when making statements based upon the fact that someone does not appear in a series of records.