How can you stop a computer program? Make math illegal?
Now, that probably just delays the world eating machine for some time, but it would be a hell of a lot harder to make anything like our top of the line models without access to massive amounts of both compute and data.
The hard problem isn't making the world eating machine. The hard problem that silicon valley doesn't give a shit about is making the world eating machine even safe enough to be on the same planet as without it melting the entire crust when you say "oh, it's a little chilly out today".
Inner alignment is completely unsolved and the pace at which we are solving any alignment issues is much, much slower than the rate we are making gains in intelligent unaligned machines.
AGI would be a somewhat different kettle of fish, and there is little political will to limit the proliferation of its precursor AI technologies (some economic interest in limiting large scale hardware deployment within China, but that isn't the same thing).
The reason your thinking fails is humans are greedy as shit and anything trained on human data will know that. All Cortana++ needs to do is tell some VC that hooking it right up to the internet will be able to make them billions of dollars and it would be game over for humanity.