Should wiring connected to absolutely nothing concern you? Absolutely!

This armoured cable was used to power a garburator under the kitchen sink at one point. This is a safety concern as it presents a possible fire and shock hazard. 

The loose electrical wire should be removed or contained in a metal junction box. Luckily the hot and neutral wires were connected together with an orange marette. 

If someone energizes this circuit the breaker in the electrical panel would trip. What if the marette is knocked off in day to day activities?