FWIW the reason why I proposed to add assert_python_ok to test.support, is that from my point of view it's just one of the many *test* support utilities defined in test.support.  I think that from Nick's point of view, assert_python_ok is just one of the many *script* support utilities defined in script_helper.
Since I'm not familiar with the other utilities of script_helper, it seemed logical to me to have it where I expect all the other general utilities to be (i.e. test.support), but I figured out that Nick has a point too.