Why is he not a nuclear rocket surgeon?

Hi,
What does this sentence mean?

I've heard of rocket scientist and rocket science, but what is a "nuclear rocket surgeon"?

If we want to say that something is not difficult, we often use one of these two comments.
It's not rocket science or You don't have to be a rocket scientist..
It's not brain surgery or You don't have to be a brain

rocket scientist -- someone who is smart enough to design and build rockets - it was an older expression for a "super geek"
rocket science - the study of building rockets; a combination of physics and engineering. These were very difficult and demanding subjects.
nuclear rocket surgeon - I have not heard this expression before. It is invented and it probably will not catch on. I guess t

Truly. Everyone knows it's Quantum Rocket Surgery.

Is there not a name also for when people unintentionally use a word out of place. Often when trying to appear inteligent.

Like rocket surgery, phonographic memory, tinterweb, the Great British public.

Do you mean malapropism?

http://www.merriam-webster.com/dictionary/malapropism

It's an expression for saying why someone who is apparently a genius, isn't doing things geniuses are supposed to be doing.
For example:
Let's say harry is a genius but works as a lowly paid salesperson.Then someone would aptly express their confusion with his predicament with this statement, "why isn't he a nuclear rocket surgeon?", the phrase nuclear-rocket-surgeon is just a exaggerati

The expression seems to be catching on: 485 Google hits (mostly from the same handful of posts, including ours!)