What was stolen? We have a binary from which we can infer source code. But we do not posses the original source code. Why should it be illegal? You still need the game's assets.
With PDF the better analogy would be producing LaTeX file(s) that correspond to that PDF, without owning the original LaTeX file(s).
With PDF the better analogy would be producing LaTeX file(s) that correspond to that PDF, without owning the original LaTeX file(s).