An important part of school is learning how to learn. It is a constant struggle with pupils to get them to actually think instead of googling for an answer.
Sometimes it feels a bit like I am a grumpy oldie telling them things like _in my day we had to look things up in books instead of using Google!_ but most of the time it’s valuable in and of itself to go through things from first principles.
(The sensehat bug was a case in point.)
As far as source code is concerned, it turned out to be quite tractable to follow the Python source code at least far enough to find the timsort.txt document.
If any of these kids go on to have technical careers, there will be plenty enough time for googling answers later on in life. Hopefully some of them will be writing the answers too.