They sneakily bought the rights from them
They already owned the rights to them, by virtue of hiring the SoundJam developers. C&G where then asked by Jeff Robins to cease distribution of SoundJam, which they did. Apple then gave C&G a bag of money as compensation (which they where under no obligation to do).
Not exactly robbing them of their code, but not exactly ethical either.
C&G only had distribution rights to SoundJam, not the code. SoundJam was chiefly written by Jeff Robbins who by then had returned to working for Apple after a few years indie.
What would we say if Apple suddenly done the same to Blitz Research?
What would I say if Mark was hired by Apple, given unlimited budget and resources to work on BlitzMAX, and release a newer and vastly improved version of iBlitz as an integral part of MacOS X Pussycat? "Good on ya'" I reckon.