Well, that's interesting. According to this article BL went missing on the 12th rather than the 13th. Still doesn't explain why his family didn't report him missing to NPPD to begin with.
People don't think of you as missing when you leave, only when you don't come back after a certain amount of time. Why do you think they should have reported him missing on the 13th? He wasn't missing then. He was out hiking or camping or meditating or getting his head right.