There is a big difference between being having vulnerabilities and being valuable attack surface. Again, I am not saying that cat and others do not provide attack surface, or even valuable attack surface, only that step 1 is not "rewrite cat".

Generally "cat" is not exposed to the internet, and if you're running a service and you said "I'm concerned about local attackers using cat" it's probably a lot easier to just put the service into some sort of environment (container, sandbox, user, whatever) that doesn't give access to cat.