OK, fair enough. I can appreciate that while getting a Jobe server up and running is straightforward enough, it is one more thing to maintain. And the fact that your Moodle server is on an outside rented server does mean that Jobe has to accessible from that server. That's the only machine it has to be accessible from, though. You should normally set the Linux firewall on the Jobe machine to prevent any other access, so it's really not vulnerable to attack in the way that the Moodle server or other web servers are.
I spent some more time testing the Ideone sandbox today, until I received this email:
Hi coderunner, you have reached a limit of free submissions this month. If you wish to submit new codes now,you can purchase a pool of submissions by visiting https://ideone.com/offer/users/. Regards, Ideone Team
So as I rather suspected, Ideone is no longer a free service and I'm not prepared to buy a package of further submissions in order to do further testing.
You're welcome to the updated version of the PHP Ideone Sandbox code if you want it, but you'll have to fix any further bugs with it yourself. Do you have shell access to the Moodle server to edit the code?
Also, aside from the fact it's not a free service, you should be warned that Ideone is nowhere near as responsive as Jobe. Each run takes at least several seconds and so questions with non-combinator templates (e.g. programs that are run multiple times with different standard input) will take a rather unacceptably long time to grade. Lastly, you need to be aware that the Ideone sandbox has never, to my knowledge, been used in a production environment so there are bound to be "interesting" things happen in some situations. With all those caveats, are you still interested? :)