You're right, and IIRC this symbol has been proposed before unsuccessfully. But recent events have called to attention the backstory behind Prince's symbol---how it was created for use as a tool to modify an unfair contract, and how that successful hack opened up the recording industry for artists---many articles were printed about it at the time (most of them missing the point), a few books were written since, lots more articles were published about it last week, and likely more books about Prince are being written now.

A code point is needed for Prince's symbol now. It's no longer merely pop culture but history and law.

Eh. As much as we like Prince, his symbol is still a brand, and Unicode should not be a permanent memorial to brands.

And here's why excluding people is nice: I'd say there's history involved in the fact that the North Korean encoding (KPS 9566) has codepoints for special decorative characters for writing "Kim Jong-Il", but Unicode isn't putting those in either.