I tried but couldn't find anything. I also tried the other bytes in the linked post. I found some results for "defaultkey" but what follows the string is "site-packages/route.py". I guess it's from some other apps and not what a normal wallet.dat file contains?
It's definitely from another application, Bitcoin-qt (today it's called Bitcoin Core) mostly use C++ and AFAIK the compiled version never include raw source source.