I think you misunderstand Sprout's meaning, and that Sprout precisely understands Wolfrom's. Sprout is actually saying just what you say: honest belief can be independent of truth or legality, but Sprout also emphasizes that from a legal point of view the statements of Arr. and McClure are mutual contradictory. An action can be ethically grey, but not legally gray (i.e., there's no such thing as bending the rules without breaking them).