Removing them because there is a replacement already is a better reason
than removing them because they give (bogus) warnings, so I'm -0 now.

As you say, tempfile is not any better from a security point of view in
the cases where tmpnam or tempnam would be used (e.g. if you want a
child process create a file whose name you specify).

Whether the tempfile.py implementation is actually better than the one
in the C library, I cannot tell (hence the -0: I don't know whether
tempfile.py or the C library wrapper should be removed). One issue I
just noticed is that tempfile.mkstemp promise of not inheriting the file
descriptor is bogus in the presence of threads and race conditions.

If the rationale for the patch is to eliminate duplication, then
os.tmpfile should be removed as well.