If an avahi publish server doesn't start, sending the SIGTERM to stap-serverd appears to do nothng, but terminating the stap-gen-cert will cause stap-serverd to stop as well. (If the publish server does start, terminating stap-serverd will kill everything, as intended.) Also, it would be nice if stap-stop-server without any PID arguments given would still terminate a stap-server if only one instance of stap-server is running.
These issues have been addressed long ago by enhancements to stap-start-server and the stap-server initscript.