Interesting concept, poor execution. The writing seems amateurish, which is strange given that Wilhelm is a veteran of the sci fi scene. I suspect this is not a work she spent much time on.
I do think it's worth drilling down on how exactly this story goes wrong, because its missteps could be instructive for other writers. Or at least, I'm taking them as instructive for me:
1. Overuse and misuse of specifics. Maybe this is just a pet peeve of mine, but if you're going to include detail in a story, that detail should serve a purpose, either by (1) imparting necessary information, or (2) improving the visceral feel of the story's world building. Here, Wilhelm packs the story with mundane minutiae, while skimping on anything remotely aesthetically pleasing.
"I called Cat on her cell phone." We don't need to specify "on her cell phone" unless it's to explain something else, like that you tried to call her landline first. It's just needless filler.
"I took out my iPad and began writing a report." You don't need to specify "iPad," or any specific device really. You can just say, "I began writing a report," or "I sat down to type my report," unless the fact that it's an iPad is somehow a weight-bearing detail. These examples sound minor, and they are, minor, taken in isolation, but when that kind of mundane specificity happens every other sentence, it's really annoying.
Not only does Wilhelm include too much useless specificity, but her use of specificity often serves as a stand-in for what could be an opportunity for more robust description. For example, "he drove up in an expensive black Buick." Ok, but what about, "The Buick he pulled out of the garage was a gorgeous machine, all buffed black curves and chrome detailing. He rolled down the window, and the warm smell of leather preceded his invitation to get in." Maybe it's just a preference -- and far be it from me to suggest that my version is anything near ideal -- but in most cases, I would prefer the author paint a picture than simply name the object. Likewise, "He requested we go to a drive-up hamburger joint. We went to a McDonald's... He had never been to a McDonald's." Here, you're just supposed to insert a picture of a McDonald's yourself, rather than have the author describe this house-bound man's first experience with the "real world." What about, "He wanted to go to a drive-up hamburger place. He'd explained how he had heard about them, but never seen one. 'Whatever you want,' I agreed, and sure enough, within a mile, the ubiquitous golden arches of a McDonald's appeared, rising out of a cluster of car wash and gas station signs like a lighted beacon on the horizon. I pulled in. He rolled down the windows, leaning out a little and breathing deeply the smell of fry oil and warm pavement. There was nothing notable about this McDonald's, just a squat building with painted brick and all the standard corporate branding. If anything, it was a little shabby, surrounded by parched ground cedars with scraggly thistles and chicory growing from cracks along the wall. In back, the garbage had been piled next to the dumpster, rather than in it, and I began to question his breathing so deeply as we pulled around to the menu." Etc. Just... don't give me lists of items. Give me something visceral to dig into.
2. Nonsense characters. I don't know how to put this more delicately, but the characters are bad. The story is told from the perspective of a researcher who has no compunction about telling you what a good researcher she is. It's pretty arrogant, and definitely violates the "show, don't tell" dictate, particularly since her research technique seems to be nothing more than Google and Wikipedia. This character has teeth-gratingly bad banter with her friend, the award-winning documentarian. There's also a guy named "Cracker Jack," which is such a bad name for a character, I don't know how to begin. Then you have the villain, who is hilariously susceptible to incompetent gaslighting. Like, it's all just nonsense. These aren't real people behaving like real people would behave, and none of it is charming or relatable.
3. The main character gives a speech about a crackpot scientific theory. Look, if anyone can't throw stones here, it's me. (Ask me about my own crackpot theories about time sometime! Do it!) But this theory is simultaneously hand-wavy and easily disproven. It doesn't engage with actual science at any point in time, and actually misrepresents basic facts. Like, time is a "real thing" in and of itself in basic physics, not just due to our phenomenological experience of it, and you have to address the math of the situation head on rather than pretending it doesn't exist. There is a way to address it (again, ask me how!), Wilhelm just doesn't do it, instead having her character simply bulldoze her haters, which makes her look a bit silly. Also, the way this information is imparted (protagonist-delivered speech) is quite cringe. You have to be more subtle than that.
Overall, this story seems more like a rough sketch that could have used more fleshing out and several more (robust) rounds of editing. I don't blame Wilhelm. To me, it seems this story was just something to get out the door towards the end of her life, and it's not representative of her other works. And it is an interesting core concept. Still, it's not a story I enjoyed, and it's not something worth emulating.