Do Tilson and Stein have more or less of a vested interest than the people who wrote the studies they are criticizing? It’s not obvious to me that they are more (or less) conflicted.
To answer your question: without other data, generally I would expect a person who works for an industry supporting institute to have greater vested interest than academics working at a university- academics mainly just want to get more funding for their individual research, while the industry is dealing with multi-billion-dollar industries and they get paid well to write articles like this. But now that I look carefully, I don't think their institute is funded directly by the nuclear power/plant industry.