OOM eat your heart out :D This is great, but there are security implication when using LD_PRELOAD--but I like it! More programs like this for parallel computing please.
A malicious user could inject memstop.so into a critical system service and delay execution--Writing a wrapper script would work, along with keeping unprivileged users from using LD_PRELOAD.
If a malicious user can control the environment of critical system services, you're already pwned. There's no actual security issue there and no value in such a wrapper script.