MacPython-OS9 has had an abort() function for quite a while now, so there's no reason to stall in an endless loop, just call abort() on a fatal error.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 3aa63e9..fa72fe8 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1323,9 +1323,6 @@
Py_FatalError(const char *msg)
{
fprintf(stderr, "Fatal Python error: %s\n", msg);
-#ifdef macintosh
- for (;;);
-#endif
#ifdef MS_WINDOWS
OutputDebugString("Fatal Python error: ");
OutputDebugString(msg);