I wouldn't be too sure about that. The original decompilations of Mario 64 and Ocarina of Time were done mostly by hand because LLMs weren't really around yet, but these kinds of projects seem perfectly suited for handing the gritty work off to AI: There is a clear output (exact binary recreation) and a straightforward path to get there (look at this assembly code and produce some C code from it). The decompilation of Twilight Princess jumped from very little to basically 100% of core code in the past year alone: https://github.com/zeldaret/tp
I have no doubt that this would be possible for MGS2 as well.
I have no doubt that this would be possible for MGS2 as well.