To have legend axes (and its children) behave the same as an ordinary axes, a workaround (ugly, I admit) is to set the tag property to empty string (and eventually userdata to []), e.g.:
plot (1:10, '-r');
lg = legend ('toto'); ch = get (lg, "children"); set (lg, "tag", ""); set (ch(2), "color", get (ch(1), "color"))
The legend position is affected but can further be adjusted.