Yep, it's non-canon. This and a few other recent running series are part of a little project or something (of which ZUN is a part of) to host fanworks on a website. The Satori manga is the only one on that site (currently) that is canonical.
Komachi being doubtful about or concerned with people dying is pretty out of character--not that she doesn't care about humans. She clearly does: she warns about potential death and she visits the world of the living often, but she also speaks of death very casually and is evidently very, very comfortable with the idea of people dying. She probably wouldn't save a human life, or sincerely worry about people dying. People die every day, and she ferries them.
Not that I dislike this take! But it's certainly not an ordinary Komachi. In canon the only times she's been legitimately upset have been when souls, not living people, are being destroyed or manipulated. She goes all the way to Tenshi when she's gathering souls in SWR, and suspects her later in WaHH when she shows up. After all, souls that are destroyed don't "die". They aren't "killed", they're obliterated, never to be reincarnated again. She also warns Kasen about her destroying vengeful spirits early in WaHH, saying Hell won't take kindly to such actions.