I don't get it...

If a plastic saddle is safe -- why wouldn't a carbon saddle?

You don't see bike frames made out of plastic, therefore one would assume that carbon is stronger.

Other than periodic inspection to ensure it isn't chipping or cracking, carbon is a great material.

Edit: The saddle pictured above, I wouldn't personally buy it. Only because I'm happy with what I have. If I was at the beach and rented a bike and it came with that, I'd ride it no questions asked.