Though, what i think Block means here is that without governmental interference science would be closer to truths, I'm not sure he words this correctly. The way in which it's worded one would think that without government the sky is the limit in prediction markets. I invite you to contrast the reasoning to the knowledge problem outlined by Hayek. Weather, and other nonlinear dynamic conditions pose great problems for prediction, especially is one operates from the view that a good prediction is gauged by an outcome that is close to mark. But, as we know, in nonlinear systems small errors grow exponentially as you increase your time horizon.   

It may be true that weather, as other systems, are deterministic but this does not imply that they may be determined. Making statements such as, "if one were to have access to all information of location and movement, etc, than the future, like the past, would be like the present...predictable" may be helpful for thought experiments, but this does nothing for the predictor. Unfortunately, though fortunately is probably a better word, there is always uncertainty (noise) within an measurement.  In spite of this we can factor in chaos for our models. 

Of course, Block would have to stipulate what he means by "weather prediction". Certainly if we limit the time frame to the next five minutes an ignoramus could predict the weather. But if Block were to mean better than now, he may be either right or wrong (see below). Longterm atmospheric modeling cannot make longterm predictions unless these predictions are extremely general. For example, we will receive snow in 2050. We know that any time series will contain randomness.