There's just no way that's true, you don't design a map with 14 levels, show that stage select to the player and then only have 8.
Metal Gear Solid 2 literally has one of the most documented developments ever. To the point that Kojima sold a "documentary game" on the PS2, the pretentious fuck.
And that thing has almost everything on it. It has the original storyboards, it has the *original* plot outline about Liquid stealing nukes in Iraq/Iran. It has the cut models of Arsenal crashing into New York. It has the cel-shaded early test character models as well as the weirder Shinkawa concept art style character model tests.
About the only things it doesn't have are the finished cutscene of Arsenal crashing into New York (if it was ever actually done) and the cut codec conversations that you can still access on the original MGS2 disk. (most of it amounts to Otacon giving Snake descriptions about cut items) mostly cause I don't think it bothered with any of the codec calls.
We know *so* much about the development that I can tell you the English dubbing sessions for MGS2 started on July 9, 2001.
I'm telling you, it was a design choice. With Kojima, if it's stupid as fuck there is a 95% chance it was a design/narrative choice.
Edit: Also, this might be a good time to link
the translation of the original game outline of MGS2, for anyone that is interested in some of the things that were actually cut. It's interesting to see how much carried over into MGS4, actually.