Fire codes require that all exits from public places open out to prevent crowds from jamming the doors closed. Storage sheds have outward opening doors so as to not obstruct access to the interior. Most residences will have an inward opening main door with an outward opening storm/screen door. Big crowds are not expected in a home.
I seriously doubt that Ken's train building will be considered a "public place". In any case, if it's allowed by local building codes, I think the outward opening door seems preferable in Ken's situation.