These examples seem somewhat contrived, but of course it comes down to the use case of the database. I'm sure Prince remained registered under his legal name on contracts, checks etc, even if he used the symbol in marketing. But a database over bodies in a morgue obviously need to be able to support unidentified bodies.
Interesting, I think you're right. According to Wikipedia, he only changed his stage name, not his legal name. The BBC didn't seem to make the distinction.
