Dean,
I do not know the chemistry behind how heated acid draws oil from a stock but it does. So does unheated acetone and whiting compond. They just do not draw out as much oil.
Heat and steam are used to cause the bonds between wood fibers to soften allowing them to realign under pressure. The bonds are reformed when they cool. This is how one, including me, can bend a 100 year old gun stock without breaking it.
When I consider the above, plus that certain acids may destroy metal but not wood, I am happy to accept under the correct conditions, Brad is able to use heated acid to draw oil from a stock. Unlike bending a stock, this is something that I will not try at home
Mark