[Natsu]

Which is funny, because the goo is actually green.

I never understood the fear of nanotech, because I see no reason that tiny robots would be any more scary or harmful than all the bacteria out there already. And the bacteria can already both self-replicate and kill us.

[VMG]

If bacteria were as powerful as nanotech, there would not be any need for nanotech. Nanotech could potentially be to bacteria what the space shuttle is to a horse.

[Natsu]

Nanotech can neither replicate nor kill us yet. It's not magic, and evolution has a huge head start on dealing with issues like powering it and self-replication. Devices at that scale are, generally, quite frail to things like stray cosmic rays or other background radiation causing them to break down.

And the space shuttles are dead; there will be no more of them. Horses, meanwhile, have survived for millions of years, so you're making the opposite point by mistake.