Cipher only cares about the object being a creature when it's encoded. After it's encoded, there are no checks regarding the object still being a creature.
The same is true for +1/+1 and -1/-1 counters, and the haunt ability.
Equipment can only be attached to creatures. If an equipment finds itself attached to an object that's not a creature, it becomes unattached as a state based action.
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"Simple questions" usually need rather complex answers, while complex questions often come down to no more than a simple "yes" or "no".
