If when riding your bike safety is the most important thing, we should all stick to our front yards and keep it under 5mph. Enjoying your ride within acceptable personal and legal standards should be the most important thing.

Music is not nearly as important as my life, but that does make them mutually exclusive or provide a analogous relationship that my life will be directly threatened by introducing music to it. Statistically we are more likely to die in the home anyway, so even with headphones in the bike could be viewed as relatively safe. Its a risk assessment exercise. it does increase risk, but an individual can mitigate that risk to an acceptable level within their own standards.