It doesn't appear to be an official release, just a leak of some sort.
it should therefore include a notice letting users know it's GPLed, and either include the source (it does not) or come with an offer for getting the source elsewhere.
so, I mean, I guess you can get the source NOW.
I remembered seeing 2000 dates but apparently this game came out in november 2001
I'd bet a lot of money this isn't the only time GPL source has ended up in a console game
There are definitely cases we know of, like Mistic's Wii ports of Humongous Entertainment that were shown to just be ScummVM (and they got sued over it)