It's not Ep3 code, it's mostly just placeholder stuff / stuff they tested with but never used / they're trolling. There's so much in the hl2sdk that was never used (and pertains to certain things like ep3 / borealis) yet people at any sight of ep3 go OMG EP3!1!1.
Well it's common knowledge that Episode 3 is being developed by the original Duke Nukem Forever team so...