Hmm. Can anyone explain why this poem is in the public domain? Lifetime of the author plus 70 years hasn't expired yet. (I'm not trying to hijack the thread

Hmm. Can anyone explain why this poem is in the public domain? Lifetime of the author plus 70 years hasn't expired yet. (I'm not trying to hijack the thread into a bunch of "copyright lasts way too long" rants. I'm just curious, if anyone knows.)