The conventionality thesis and the asynchronous convention for the one-way speed of light (ASC) has been presented as a biblical creationist explanation for how light from the most distant sources in the cosmos reached Earth within the 6,000 years since the Creation, as determined from a straightforward reading of the Genesis account. There is no conflict with the true age of the universe because it simply is counted off by the years since creation.,,
The conventionality thesis in Special Relativity relates to the synchronisation of clocks separated by a distance. It involves to the notion that the one-way speed of light, provided the two-way speed is c, can only be chosen by a convention, since it is impossible in principle to measure it.
The first issue relates not so much to the science but to the mindset of the hearer when the topic is discussed. There seems to be in many of us an innate bias against accepting that the events (in light from stars, galaxies etc) we see in the cosmos are the same age as the earth and solar system. The idea is that all we see in the cosmos is occurring now, and not in some past epoch of time. However due to our education among other factors we are biased into believing the starlight coming from the cosmos travels at a fixed speed of about 300,000 km/s and because of the distances involved it must have taken billions of years to reach Earth. We believe this even though it has never been measured.
Last year I had the opportunity to share a PowerPoint talk titled “Can we see into the past?” with a small group of friends who were all solidly biblical creationist in worldview. After I gave the PowerPoint presentation some questions were asked and one person, who does have some science training, said that he just could not get his head around it. I respect that but I believe it is a case where a little knowledge can be dangerous. In some cases a prior knowledge has led to a closely held belief, or an innate bias, which in turn can close off a person’s mind to new ideas without any logical reason. Such situations are well documented in science, particularly in fields that are undergoing revolutionary transitions. For example the case of phlogiston.
Another man in that small group, who is physically blind and could not see my PowerPoint slides (so he did not have the advantage that the sighted people did), said that he had no problem understanding it. He said that he had had no science education and did not have any preconceived ideas (for example that the one-way speed of light must be finite, isotropic and equal to c, the measured two-way speed).