Solution: It seems that despite some "> /dev/null" bits, I somehow wasn't closing the file descriptors being used for STDIN/STDERR/STDOUT. Since the original process was being launched through some funkadelic pipe interface, it was waiting for output to be closed--not for the script to terminate.

Solution was this little internal shell script bit, which seems to close STDOUT and STDERR from within a running script.
Code:
exec >&- 2>&-