He doesn't owe it to you, he doesn't owe it to me. That makes two of us. Let's imagine we're not unusual in that regard. Who does he owe a warning, then?
when you release open source code there's a kind of implied promise that you don't suddenly delete the master repo in a fit of internet pique.
You're making a lot of assumptions, not least among them _why's motivations (should they even exist) for dropping off your radar. Again, he doesn't owe you an explanation or a warning.
You were a user, not a co-owner of the projects, not an extensive financial donor (most likely), not an employer. The relationship is entirely one way. _why gives you things, you say "thank you", and move on. This is also the Internet we're talking about, if someone decides the content (repository or writing) should be made available again, it will happen.