I agree, for that level of integration you want a "gameplay scripting system", whereas Lobster is more of a general purpose programming language that happens to be a nice starting point for simple games & engines. I don't think in its current form it is a great language for a large AAA team anyway, because of its heavy reliance on type inference and lack of separate compilation.
The language could of course be adopted to these use cases, it simply hasn't, so far.
Doing simulation on a separate thread from main/rendering is something it is already set up to do (multi-threading uses separate memory spaces so it is easy to ensure there's no data races between the two).
