When attempting to play crop cards with other classes, which can be attained through a variety of means, they don't seem to work. My friend and I through our combined experience, tried 6 different characters, including the base classes of defect and watcher. Considering this, it's safe to rule out everything else but the mod itself. This should be fixed to make it more inline with other mods, as otherwise, it encourages disablement when not directly in use.