That's the question. Or I really am not understanding what all is in there.
But what I understand (if correct) is that the files in .git/objects are
such that the subdirectory name is the first two hex characters of the
SHA1SUM value of the contents, the file name within that subdirectory are
the last 38 characters. And the contents of the file are a compressed
version of the data. In any case, once the file is created, the contents
are never updated. In fact, if they were updated, git would likely be
royally messed up. If the original file is modified, a new SHA1SUM file is
generated. So, why doesn't git just mark the files as "read only"?
This is just a curiosity question.