Depends on what you consider "hiding the research". A fishing expedition through a scientist's personal correspondence is an invitation to judge his work on *political* grounds.
In science your personal beliefs, relationships, and biography are irrelevant. There are evangelical Christian climate scientists who believe climate won't change because that would contradict God's will as expressed in the Bible. These scientists may be regarded as religious crackpots by their peers, but that hasn't prevented them from publishing in the same peer-reviewed journals as everyone else. Since their papers invariably are climate-change skeptic, clearly they are publishing work which supports their religious beliefs. But their motivations don't matter. What matters is in their scientific publications.
In 1988, Gary Hart's presidential bid and political career were ruined when he was photographed cavorting on a yacht named "Monkey Business" with a woman that wasn't his wife. Now I didn't care how many bimbos he was boinking, but a lot of people *did*, which made it a political issue (albeit a stupid one in my opinion). Do we really want to use the coercive power of the state to dig through the private lives of controversial scientists?
It's a pretense that that would serve any scientific purpose. Maybe Mann is intent on overthrowing capitalism and creating a socialist utopia. That would be relevant if he were running for dogcatcher, but it's irrelevant to what's in his scientific papers. Scientists publish papers all the time with ulterior motives, not the least of which is that they're being paid to do research that makes corporate sponsors happy. As long as what's in the paper passes muster, it's still science.