Discussing this elsewhere, I was directed to this web page.
reasons.org
I was surprised to find an article that does at least make some attempt to address the issue.
The author summaries the situation well:
The "RTB Creation Model for Genomics" is explain, to some degree here.
RTB are an old earth creationism group. On that basis I think they believe in special creation - each "kind" was created in isolation - but that this happened over billions of years, so, for example, God created humans a couple of million years ago. The salient point here is that they reject common descent; they believe chimps and humans are not genetically related, and so reject the evolutionary theory noted above.
With regards to the Vitamin C Pseudogene, they say:
That is to say, they are claiming the same mutations happened to occur in these three species.
That is not completely unreasonable; some mutation are indeed more likely than others. They point to a mutation in guinea pigs that is identical to one of those in the primate vitamin C pseudogene, and evolutionary biologists agree with RTB that this was due to an independent event.
However the problem is that it still fails to explain the full pattern of mutations seen. For one thing, we are not just talking about humans, chimpanzees, and orangutans. This same pattern of mutations is see in gibbons, macaques, marmosets and owl monkeys, as this article discusses.
In particular look at this figure, which shows the pattern of mutations that break the gene. It is the same for the primates, and quite different for guinea pigs.
While RTB have at least made a stab at the Vitamin C Pseudogene - I am not aware of any other creationists trying to - I think their hypothesis fails to give anything more than a façade of an explanation.
Pseudogenes and the Origin of Humanity: A Response to the Venema Critique of the RTB Human Origins Model, Part 7
For over a month, I have been responding to biologist Dennis Venema’s criticisms of the RTB human origins model. (See my previous posts: part 1, part 2, part 3, part 4, part 5, and part 6.)

I was surprised to find an article that does at least make some attempt to address the issue.
The author summaries the situation well:
Humans and primates (including chimps) share many of the same mutations in the GLO pseudogene. Evolutionary biologists argue that these shared errors evince common descent and the shared ancestry of humans and the great apes. But if this defect arose before humans and chimp lineages diverged from a common ancestor, it would explain why both organisms share the same GLO pseudogene. Why would a Creator introduce exactly the same defective, nonfunctional DNA in both humans and chimpanzees?
The "RTB Creation Model for Genomics" is explain, to some degree here.
The assumption that undergirds our model is that a Creator is responsible for life’s origin and history. As such, the genomes of organisms have been created via God’s direct intervention. But once created, genomes are subjected to physical, chemical, and biochemical events that can induce changes in their structure.
RTB are an old earth creationism group. On that basis I think they believe in special creation - each "kind" was created in isolation - but that this happened over billions of years, so, for example, God created humans a couple of million years ago. The salient point here is that they reject common descent; they believe chimps and humans are not genetically related, and so reject the evolutionary theory noted above.
With regards to the Vitamin C Pseudogene, they say:
The RTB genomics model offers a different explanation for the similarities in the primate DNA sequences. The shared features are interpreted as the outworking of nonrandom, reproducible changes that happened independently in humans, chimpanzees, and orangutans.
That is to say, they are claiming the same mutations happened to occur in these three species.
That is not completely unreasonable; some mutation are indeed more likely than others. They point to a mutation in guinea pigs that is identical to one of those in the primate vitamin C pseudogene, and evolutionary biologists agree with RTB that this was due to an independent event.
However the problem is that it still fails to explain the full pattern of mutations seen. For one thing, we are not just talking about humans, chimpanzees, and orangutans. This same pattern of mutations is see in gibbons, macaques, marmosets and owl monkeys, as this article discusses.
In particular look at this figure, which shows the pattern of mutations that break the gene. It is the same for the primates, and quite different for guinea pigs.
PubMed Central Image Viewer.
www.ncbi.nlm.nih.gov
While RTB have at least made a stab at the Vitamin C Pseudogene - I am not aware of any other creationists trying to - I think their hypothesis fails to give anything more than a façade of an explanation.