I guess my initial questions, if there are indeed folks with robust knowledge in this field, would cluster around the following:
This is not my field. I do have a some general thoughts. I think mature creation can help with a lot of the radioactive decay stuff. I don't see the heat objection to accelerated decay to be a problem either. Creation is a miracle week with miracles happening, so a miracle could protect from the energy released.
As for the flood, it is within the bounds of historical reformed thought to consider a miracle during the Flood to preserve the trees, so it seems reasonable to me to extend that idea to protection from the energy released due to accelerated decay during the Flood. I know though that many prefer to find an actual testable model, and there may be one, for all I know. (I am not advocating for a solution; just explaining why I find the heat objection unconvincing)
Poole's commentary on Genesis 8. I thought I remembered him talking about how the Israelites' shoes were preserved and so the trees during the flood might be preserved by a powerful providence. However, he does not say that here, so I may be remembering something else.
"Quest. Whence was this leaf, when trees had been so generally overthrown and rooted up by the deluge?
Answ.
1. Many trees might be preserved by an advantageous situation, between the rocks or hills which broke the force of the waters.
2. It is probable that God, by his powerful providence, preserved the plants and trees for future ages; and therefore there is no mention of any of their roots or seeds preserved in the ark.
3. The olive-tree especially will not only stand, but live and flourish under the waters, as Pliny, 1. 13. c. 25, and 16. 20, and Theophrastus, 4. 8, observe. Add, that the word here rendered leaf signifies also a tender branch."
I adhere to a global flood on textual reasons. I do find it fascinating though that water at levels that are high elevation today is acknowledged even in the secular realm, e.g., I'm thinking about the rocky formations out in the West in Utah, Arizona, and Nevada. I recall as well while out in Utah, I spoke with one of the people at a dinosaur tracks museum about the pattern of the footprints. The tracks seemed rather chaotic, and it was explained to me that they were running. I asked how some footprints were able to cross on top of others: it was explained to me that they would have had to been made within a short amount of time. I asked how short, and I was told these kinds of tracks would have to have been made and then flooded very quickly: flooded within hours to a day (or maybe she said two?) at most after they were made. Lots of fossilized imprints from raindrops in that museum as well, and a fossilized track from a dinosaur resting, likely after injury. I recall seeing tracks while out in the wild that were pointed in the direction of higher ground: probably the terrain there has changed, so it could be a useless observation, but I found it striking nonetheless at the time. All this to say: rapid burial--of which flooding is one way for that to happen--is the mainstream explanation for fossil-making, but the rapid burials and floodings are not connected together into a single global flood.
I think I remember searching some Creationist pages after that musuem and seeing that there is a view that the global food happened in stages, so that there could be flooding and recession locally at various places before the whole globe became flooded.
I have no idea how sound any of this is scientifically. Certainly some of it would not be scientific due to the miraculous nature and speculation about what may have happened with little to no textual data.