I'm not sure how implementation is "completely irrelevant"; if that were the case then the entire conversation is essentially irrelevant as we could potentially implement any compiled language as an interpreted language.

The piece I quoted indicates to me that the parent possibly does not understand this about JavaScript since they stated the compilation cost of JavaScript "is zero" that implies that JavaScript is not compiled. If there is a compilation step then some cost is incurred no matter how low.

It was further supported that the parent may not understand JavaScript is typically compiled when they followed on with "cost being completely amortized with everything happening directly at runtime". That would indicate that all of the cost is incurred/paid at runtime rather than in the compile step which is simply false.

The parent is talking about the costs and benefits of AOT compilation versus the lack. Whether the interpreted language uses a JIT has nothing to do with that trade-off. That's why it's irrelevant.

Also, that the parent bothered specifying "AOT" in the first place is proof enough the entire basis of your belief in their understanding of things is utterly groundless. This would be clearer to you if you understood that JIT compilation cost is amortized, as the parent alludes, and that it doesn't happen in "a" compilation step.