You, like most of the internet, believe that Cage (it's always about him and rarely about the games, lol) is some kind of idiot with a pen and has no idea how a game should be made. Personally, I was disappointed at first with HR but then I spent some time to think and I did end with this easy explanation that solve everything. I'm happy, end of story. My personal interpretation has a lot to do with how our medium can be used because it's something I'm very interested in. A very easier interpretation (or a fact, my memory isn't that fresh) that you will like more, states that the thoughts of the killer are ambiguous. I don't like it because I can prove that sometimes the killer is just lying, blatantly.
I explained what I think, I gave examples and references in the game. All I had as answer is "Cage is a shitty writer"/"but the cut content.." etc, like always. The're not exactly the answers I hope for. If someone can prove me wrong with real examples, I'd raise the white flag immediately. Mentioning some kind of "universal game rules" it's pointless when the character we're talking about
does break those rules, like every character in videogames that has a direct connection with the players that goes beyond the input (it means they're not just puppets we can control). Difference is that this time the guy is using those very tools against us and he's playable at the same time, easy as that. Could've been better? Absolutely, but it's not as broken as people claim it to be in my opinion.
Ending with a honest note: I always thought that it's almost funny to believe that a man, anyone in this industry, could be so dumb and stupid to the point he didn't realize the crazy amount of inconsistencies he was writing, to the point he wrote about a killer that didn't know to be the killer, cut out some key content and released the game because fuck you, it's too late to change things now!
And by the way, MGS2 is meant to give a clear message in the ending, there's not much room for interpretation there. I talked about Fortune's clip.