It's a simple question.

(IFF) you don't have a reason (THEN) you are by definition an un-reasonable person (a person who acts without reasons).

(IFF) you claim to have a reason but refuse to reveal it, claiming it is secret, or unimportant, or "just too complicated to explain" (THEN) your unrevealed reason is functionally-indistinguishable from NO reason (AND) you are therefore functionally-indistinguishable from an un-reasonable person (a person who acts without reasons).