That's his point; the product itself is definitely not worth this money.
We're in a bubble because these internet companies like Google and Facebook are still trying to adapt revenues to this "mobile" thing. They're bombarded with talk about how people are using apps more and browsers less and how they need to be deeper inside this market.
In my opinion, it's all analyst and ill-informed-shareholder bunk. The bubble is that there's this new technological nirvana over the horizon and once we get there the internet as we know it will change and these companies will be in uncertain situations.
Personally, I don't like this news. I think that's a grotesque figure. At least double what it's worth.
I'm also hugely skeptical of their position in Asia. The most attractive market there is obviously China (with India a close second). China has a tendency to come up with their own versions of Google, Facebook, Twitter, etc and push those over the "originals". WhatsApp is nothing special; if it is acquired by Google, I'd expect Sinicised alternatives to suddenly become very popular.
