> What a compiler needs is not determinism, but semantic closure.

No, a compiler needs determinism. The article is quite correct on this point: if you can't trust that the output of a tool will be consistent, you can't use it as a building block. A stochastic compiler is simply not fit for purpose.

Compiler output can be inconsistent and correct. For any source code there is an infinite number of machine code sequences that maintain the semantic constraints of the source code. Correctness is defined semantically, not by consistency.