So at the core of it, the previous paper depended on adding a lot more turbines into existing dams so that they could be burstier, and didn't provide justification for, or even really mention the need for, the ability to add that many turbines.

This got called a "modeling error", which among other things made him mad enough to sue for libel.

Well, quality of legal decisions aside, one of the main points of the new paper is that it's "suggesting several different solutions for stabilizing energy produced with 100 percent clean, renewable sources, including solutions with no added hydropower turbines and no storage in water, ice or rocks."

Not taking sides in this debate (which is over whether or not nuclear power should be used), however the paper has four authors and in the introduction they say:

"The main purpose of this study is to explore whether low-cost mixes using 100% WWS can match energy demand with intermittent supply, not to prescribe the only possible future energy mix in each region. Indeed, many different future scenarios can be constructed depending on the objective. The objective here is to determine whether a 100% WWS system, which we believe maximizes air quality and climate change benefits while minimizing catastrophic risk relative to systems using other technologies, can deliver energy reliably at a reasonable business cost worldwide."

So either way, if their modeling is good, it is still a useful assessment of options.