The researchers needed a study to figure this out?

Environmentalism, generally, is emotionally centered much more on being anti-human than pro-environment. Being environmentally-conscious is one thing. Standing in front of trees to prevent their harvesting, or demanding punishment for anyone altering their land because an "endangered species" is on it? That's another thing entirely.

Similarly, feminism is to a large degree centered far more on being anti-male than pro-female. And considering the vindictiveness and outright intellectual dishonesty that usually is part of the feminist package, I'd wager that the study showed even more dislike of stereotypical feminists than of stereotypical environmentalists.

When you basically hate most of humanity (or just a ubiquitous half of humanity,) then it's no surprise that people dislike you and want to distance themselves from you, and everything associated with you, no matter how hard you try to hide the core emotion.