As written, this is up to GM interpretation. I'm generally fine with fire damage stacking to an extent, but there's only so much fire that someone can be on. The Meat Seam is also not particularly flammable---molotovs thrown on it will burn for a bit, but it won't take stacking d4 damage per Round forever.
Now, if the players excavate the Meat Seam and pour gallons of gasoline on it and set it on fire, that's different. That would do more significant damage, as would methodically dynamiting it. An organized and determined military could kill the Meat in a day, with some casualties.