Interesting that they'd use higan/bsnes - the most accurate SNES emulator publicly available - to run a bootrom for a system with completely different hardware. The only actual prototypes I've seen weren't add-ons but combination consoles themselves, which I'm guessing took some liberties. The fact that bsnes doesn't throw up some sort of error when the ROM should be throwing unknown code at it trying to load something that doesn't exist is suspicious. The framing of the error code is also odd; if it were run off a SNES with a CD system attached I could see something like that, but if the only development units were standalone the CD units would always be integrated - I'd expect a more verbose error for debugging, not something framed for UI pleasantries.
Additionally, it bugs me that the internal version numbering is apparently v0.95; if it was a public release that'd be sensible, but for internal testing I'd suspect a stamp of the build date would be a lot more useful, and at the very least was common with some beta builds of Nintendo games; I can't say if Sony did or does the same, though.
tl;dr this looks too much like release-ready code than something designed for testing a system that never went into production, and that's more than suspicion enough. I'm thinking someone was a month early.