This only affects that one interview pad you ran it in. We can make it hard to do stuff like this but one can always find a way. And it's fine too because these commands affect that user only.
Yes, we limit the resources we give to demo containers. So isolation and limited resources should be enough to prevent most malicious codes (like forkbombs, DDOS scripts, etc). Feel free to play with it. We would love to hear if you find something that can cause trouble!