there are a whole lot of unknowns in the whole debate, many of which could have unpleasant (to say the least) consequences. Brushing the entire field of climate science aside and declaring that all of our problems can be solved by pumping sulfur dioxide into the atmosphere is wildly irresponsible.
I think the article says just that:
Myhrvold is not arguing for an immediate deployment of the sulphur shield but, rather, that technologies like it be researched and tested so they are ready to use if the worst climate predictions come true.
It seems to me that any objection to this reasoning is really in favor of what we're doing now, which to run around in circles crying that the sky is falling, and claiming that the only possible solution is to pretty much destroy our way of life.
I certainly prefer the Myhrvold approach, of thinking outside the box and challenging others to react, than the Gore fear-mongering.