The parent didn't say "everything is random", nor anything that absolutely requires this viewpoint.

To declare that "everything is choice" strikes me as putting one's beliefs ahead of inquiry.

Indeed, when I say life has no meaning, I don't mean that it is devoid of rules. Quite the contrary is true, since our modern life revolves around mathematics. In that sense, the universe is exquisitely meaningful, it's full of mathematical meaning, but that's not massively useful for us humans trying to figure out how to spend our time.

At the small scale, the world is unpredictable. As the scale grows, for well behaved linear systems the law of large numbers kicks in, and you get predictable, mathematical behavior. For complex nonlinear systems, however, the unpredictability of the small scale can "propagate up" and render the system at the large scale completely unpredictable.

Remember that mathematics is just a model, not the territory. For starters, you have incompleteness; for any formal system you can make true statements that are unprovable. Additionally, two constructs which are central to mathematical analysis, infinity and truth, don't exist.

For hundreds of years epicycles were used to model the orbits of the planets. Now we're elevating grand theories that embed the universe in an 11-dimensional manifold.

"To the best of our knowledge, we're just robots"

Due to Bell's theorem, we know that either there is inherent uncertainty in the universe, or the whole bedrock of science gets called into question. If properly informed by physics, the view that we are robots must follow from the view that the uncertainty in nature is uncontrolled, i.e. purely random according to some distribution. Given that we have a subjective experience of choice, this presents the alternate hypothesis that the uncertainty is the result of choice constrained by preference. These aren't the only two possible hypotheses, but remember that all hidden variable models have been effectively ruled out, so no deterministic hypothesis is permissible. I would of course love to hear any plausible alternatives you could present.