This feels much more comforting to me than scary; I think the latter sentiment derives from the subject matter, because death is still treated as something to be feared, even reviled. The mood here, though, is so intimate and warm. The palette certainly helps, with the actual temperature of the pigments in conjunction with the muted tones and soft focus. Cool shadows might have significantly altered the mood, yet even the darkness has a character of gentle heat, or homeliness.
But look at the figures: the old man is reclined, his face and body relaxed but for the gentle clasping of his hands. Prayer? Thanks? It's hard to tell specifically, but that is not the comportment of someone in fear. And while at first glance Death is looming over the man, a closer examination reveals more care and compassion than threat. Rather than a completely bare skeleton, this depiction of Death appears to still have skin and sinew. Some facial features are missing, but—similarly to the man's pose—the ones that are there and their arrangement do not suggest malice, and neither do the hands. One is supporting the figure on the back of the chair/bed(?), with its fingers held loosely, while the other moves a curtain. Whether the curtain is being open or closed, I couldn't say. Whatever the case is, what I feel here is Death coming to the man, saying, "It will be time to go soon. I'll be there to receive you when you're ready." This is the kind of positioning I might use to depict a parent tucking a child in bed for the night, soon to be followed with a kiss on the forehead.