I don't have anything against making it open source.
Though I doubt it would be useful as a learning tool. Xbox 360 optimizations pervade (and massively complicate) the entire code base, possibly up to 75% of the code is written the way it is in order to have the game run well (or run at all) on the 360. Large chunks of code, often very complex, often multi-threaded, exist solely as 360 optimizations. Particularly around dealing with the limited 360 RAM, the 360 garbage collector and the 360 file system. Most of the code doesn't make sense in the context of PC development.
To put it another way, if I was to write the program again for the PC, the code base would be very very different, and a lot simpler.
I'll look into what kind of "ongoing" effort is required to open the source on one of my Github repositories.