Yes that's my understanding too JD, and Keats certainly did die in 1921, spot on!
I remember reading "The Outsider" and thinking it a fine piece of writing although like Foxbat predictable in a way. I also think it strongly reflects HPL's own sense of alienation and loss he felt throughout his own life.
I feel some Keats upon me...
That night the Baron dreamt of many a woe; And all his warrior-guests, with shade and form Of witch, and daemon, and large coffin-worm, Were long be-nightmared.