I tend to agree with him. I don't see why we're in such a hurry to "seek out new life and boldly go where no man has gone before..."
I know we as humans are inquisitive and have a sense of adventure and exploration to us. But are we really ready for this? And it's not even something like that i worry about. Forget some hideous looking creature, its what you can't see that's just as frightening. Who knows what kind of bacteria we may accidentally, or purposely bring back, and what can happen once it's here. Could make ebola or the Black Plague look like a mild case of the sniffles.
But having said that, the little boy in me would still give anything to be an astronaut and explore the galaxy.