Doesn't the chain created go under the rule "don't just negate"?

The first sentence is diagrammed as: take seriously - writer knows city well writer does not know city well - no trust writer Then, a bigger chain is created as: take seriously - writer knows city will - trust writer ... Doesn't the that fall under the rule "don't just negate" since we grabbed the contrapositive of the first sentence (writer does not know city well - no trust writer) and simply negated both sides to make it fit into the bigger chain (knows city well - trust writer) ? I know that the answer choice still stands, but I am just confused about the logic here