First time I hear of that theory, do you have any references into the literature?
I have always interpreted the passage literally, as a reenactment of what the citizens of Jerusalem would have to endure while under siege by the forces of King Nebukadnezar.
Cowpats are what poor people used as fuel. It was a common practice in India till about 20 years ago. Mix cow dung with hay, make it flat, dry it and you can use it as fuel. I am sure it is not India specific thing.
The same cowpat is also used for to burn the offerings in the temples.
I have always interpreted the passage literally, as a reenactment of what the citizens of Jerusalem would have to endure while under siege by the forces of King Nebukadnezar.