When introducing kids to programming in a classroom environment, hacking the Linux kernel is a completely OTT scenario. And Linux will still be available and probably the most popular OS to be installed on RPis, for those kids who are the next Linus Torvalds.

naturally everyone wants to avoid a situation where people are afraid to try out different operating systems. instilling open mindedness and eagerness to learn new things, to kids, the idea that the OS isn't important it's what you can make it do... will stand them in better stead than leaving them with the idea that Windows or Apple or whatever, is the only way it's done.