Seems reasonable to assume that the normal meaning is meant. At least, I don't consider my computer frozen if it doesn't do anything until I tell it to. (It's more likely that my computer thinks I'm frozen most of the time...

)
Also good to realize that actual users of the system have a different experience than what we have when we connect to one from the outside. From just playing around with the server we have access to, it is clear that some limits have been imposed on outside connections, likely to prevent excessive use of resources.
I think the core point is that this user claims to have made a syscall do something more interesting than it seems to do at first glance. You might not be able to get it to hang forever, but perhaps you'll will see some behavior you can't explain yet.