Really? I think most of his stories have a bad end, it's just that some of them have had follow-ups where the women who had a bad end were rescued...only for more bad things to happen. (Like the spider stories.)
(Apologies in advance for all the quotes, it's easier this way instead of explaining what ZeroGravitas said with my own words)
For example, ZeroGravitas explained on his Pixiv that the spider stories (the Rescue Party stories, which are probably his longest stories, and my favorite ones), have a good ending of some sort. On the last post of the Rescue Party stories he wrote "And this is how it all ends. The spiders get away through the vent in the shower (the way it got in in the first place), the APC is on it's way back to base on autopilot with a special cargo, everybody lives and all is well with the world."
And in the comments, when someone asks "But will there be quarantine protocols when the APC reaches the base, or is the base just outright doomed?" he answers with "The base is fine, the APC will be quarantined. The baby spiders will be collected, domesticated and assigned to other units after training" Even the spiders get a good ending

.
Even the Biolab story, in the last post he wrote "They are one with the blob. I suppose this is not a terrible way to pass the time until a hazmat rescue team arrives." Which obviously implies that they're fine and they're about to be rescued.
Marine Biology? Similar thing to the Lillies story, the creature lets the girl go.
I'm not saying it happens everytime (I'd say more than half the times, especially in the last couple of years), but even when there isn't a "canonincally" good ending, he often leaves the option to imagine one, if you read his Pixiv posts.