The question is only ridiculous is omnipotence itself is a flawed concept. If omnipotence was not flawed, then it could stand up against this question. This question demonstrates that an omnipotent being is logically impossible by showing that, being omnipotent, it can create anything that is not internally logically contradictory, and there is no internal logical contradiction to a rock being heavy, or, to avoid semantics, a bar of metal being difficult to bend. It's only when you introduce omnipotence into the equation that the problem arises, meaning that omnipotence is itself a flawed concept.
This is what he's trying to say Exilement, it's the main point of the entire thread only laid out in a simplified format.
The only issue is that there are a few other things you could throw in that are plausible ideas that would have a similar effect.
Like if the universe is expanding, what is the universe is expanding into? Or the idea that the universe goes on forever. It's only when presented with ideas that our minds can't wrap around that we start to think of things as being illogical, but that isn't really the case.
But just because we don't understand it doesn't make it illogical, it's just a complicating variable we haven't figured out yet, and may never will.