The problem with the concept of volcanic climate change is that it tends to be one of the strongest instances of confirmation bias. You can see this in the phrasing: "They found that eight of ten large uprisings happened within two years of a volcanic eruption." You can make a game of it: pick a climatic change and find the volcanic eruption that causes it. But that ignores the flip side; volcanic eruptions are so frequent that you can usually find sufficiently close, especially if you're willing to be very open with proximity and scale.

When you start by picking large-scale volcanic eruptions and then try to find the climatic fallout, the link seems far less clear. Of the four largest eruptions in modern times, only the 1815 eruption of Mount Tambora is clearly linked with severe fallout (the Year Without a Summer). The eruptions of Novarupta, Krakatoa, Pinatubo, and Santa Maria don't show anywhere near that level of disruption, dispute being only somewhat less powerful.