1. Choice of language only matters up to an additive constant (e.g. you could just write a simulator so language A can run language B).
2. If you want something with less physical grounding, you could use lambda calculus instead of Turing machines.
3. Kolmogorov Complexity and Shannon Entropy are compared with one another because they both are talking about the same thing: optimal compression. Kolmogorov Complexity talks about the compressibility of individual objects and Shannon Entropy talks about compressibility of streams of i.i.d. random variables.
Most people that study AI existential risk specifically are studying it due to concerns about AI x-risk. So the list of relevant AI x-risk experts will be subject to massive selection effects.
If instead you want to consider the highest status/most famous people working on AI in general, then the list of signatories here is a pretty good summary. From my flawed perspective as a casual AI enthusiast, Yann LeCun and Jürgen Schmidhuber are the most glaring omissions (and both have publicly stated their lack of concern about AI x-risk).
Of course, the highest status people aren't necessarily the most relevant people. Unfortunately, it's more difficult for me to judge relevance than fame.
Boiling it down to a single sentence reduces ambiguity. Also, given that AI x-risk analysis is essentially pre-paradigmatic, many of the signatories probably disagree about the details.
At this point, I think it's obvious that concern about AI existential risk isn't a position reserved for industry shills and ignorant idiots.
I mean... that's not even debatable. Geoffrey Hinton and Yoshua Bengio aren't financially motivated to talk about AI x-risk and aren't ignorant idiots. In fact, they both have natural reasons to not talk about AI x-risk.
2. If you want something with less physical grounding, you could use lambda calculus instead of Turing machines.
3. Kolmogorov Complexity and Shannon Entropy are compared with one another because they both are talking about the same thing: optimal compression. Kolmogorov Complexity talks about the compressibility of individual objects and Shannon Entropy talks about compressibility of streams of i.i.d. random variables.