First of all, a minor point - the interview with Hansen is from 2009, if not earlier. It has always been available on the interwebnet. Why is it only now being honoured by Watts? Is he, perchance, finding very little at the bottle of that barrell he is vigorously scraping?
If you actually read what Hansen said, he did not claim Earth's oceans are going to boil as a result of human activity. The crucial passage:
A runaway greenhouse effect means once the planet gets warmer and warmer, then the oceans begin to evaporate. And water vapor is a very strong greenhouse gas, even more powerful than carbon dioxide. So you can get to a situation where it just -- the oceans will begin to boil, and the planet becomes so hot that the ocean ends up in the atmosphere. And that happened to Venus.He's describing, in response to a direct question asking him to explain what the runaway greenhouse effect was, what a runaway green effect is. he is not saying this will happen on Earth. He cites Venus as an example. He is not saying this is what will happen on Earth, and he is not at odds with Houghton.
Watts tries to shore up his shonky argument with a bit of misdirection, bringing up the very tired, CO2-levels--were-higher-in-the-past-and-the-oceans-didn't-boil-then-did-they non-argument. Yes, Anthony, and the atmosphere was very different then, full of all sorts of particulate crap from volcanoes, and probably unbreathable. That balanced out the CO2. But I don't think we want to go there, since our lungs aren't adapted to breathing in that sort of gunk. Anyway, it is a strawman. Hansen is not claiming Human CO2 will cause oceans to boil. He says massive increase in atmospheric water vapour, from melting icesheets, will cause the oceans to boil. The question is, whether the temperature increase from CO2 released from human activity, will be enough to start the processes.
Still, this seems to be a popular meme -of-the-moment. But at least we can be assured anyone referring to it is a hard core, braindead denier.