I went through this dialog with TSA some months ago when I was preparing for a trip. No liquid fuels, no gaseous fuels, and no solid fuels.
So, I asked about solids that were burnable, like wood or wax. They said no solid fuels. Then I pointed out that wooden cargo pallets go into the aircraft all the time. How about a wax dinner candle?
At that stage of the discussion, I think they got mad at my argument. They pointed out that despite everything that was shown in black and white about prohibited stuff, the final inspector has the discretionary power to yank something out. They started to refer me to MSDS sheets, and all that. Then TSA referred me to DOT, and there is one person at DOT that can look at the MSDS sheet and say "yes" or "no" about special substances. Still, TSA has the right to yank it. I concluded that it is a no-win situation.