"The clarity and vertical collimation of the shroud image have not been fully explained by laws of gaseous diffusion, despite the mentions of Brownian motion and whatever else. Has anyone attempted to replicate the linen and create a reasonable image with an amine-derivative gas point source?"
I agree.
One of the the things we have to be prepared for, though, is the conclusion that the image was indeed produced by a Maillard reaction, but that no plausible models of gaseous diffusion can explain the clarity of the image. In other words, a natural process could have created the image, but a natural process might not be able to convincingly explain the remarkable artistic composition of the image.
We could end up with a natural process that could have produced the Shroud with a nearly zero probability that it actually happened that way.
If that happens, we must resist the tendency to force the data and say: "Well, since the Shroud exists, and the natural process explains its existence, the probabilities must have aligned such that it happened." It may be that the truth is that we have a natural photograph of a miracle.
We must be skeptical, but we must not be deterministic and assert, a priori, that the Shroud MUST have been made by a random natural process. Because maybe it was made by a non-human but nevertheless DIRECTED natural process. We won't ever be able to positively assert that is the case, at least not in this life anyway. But we must not fall into the trap of asserting that there cannot be a non-human intelligence that guided nature to make the image.
I'm not yet prepared to make any assertions on that issue one way or the other with respect to the shroud.
Wilson's theory is as yet very new, and so far many of the objections raised to it are not strong enough to discard the theory until all the possibilities have been thoroughly examined. Once that has been done there may be a completely naturalistic forgery explanation with a probability much higher than the near-zero probability of the Maillard theory in its current form. Or not. Time will tell.
If the Wilson theory is discarded at this stage based on the weaknesses presented so far, then I would suggest that the authenticity arguments (based on the Maillard theory) are just as weak and could also be discarded.