I don’t buy that the patent office requires anything of the sort. Sounds like a BS excuse to explain the lack of an actual product/working model.
His argument is that, since the patent office is refusing the patent on an important aspect, then he must handle it as a trade secret.
Good luck getting the building codes people and insurance agencies to allow residential use of something with a self-destruct module. He'll be much better off doing a power plant and selling the power.