Many environmentalists hold Christianity in complete contempt for destroying nature because of texts like Genesis 1 where God commands Adam and Even to subdue and fill the earth. And then they turn to Assisi as the one exception to the general rule that they wish more Christians would follow ...
If they "hold Christianity in complete contempt" would they really bother offering St. Francis of Assisi as a positive example they'd want Christians to follow? I suggest environmentalists are a more diverse group and plenty of those who are recommending St. Francis as a positive model are Christians themselves. Others who have "complete contempt" for Christianity may not bother with proposing examples for Christians.
It sounds like you're thinking in monolithic terms, good Christianity endeavoring to obey God and dominate and subdue the earth, and bad pagan environmentalists who despise Christians and their God and worship the earth. Most people probably don't fit in either category, but somewhere in between. In practical terms, "dominion" can't simply mean "Earth is yours. Take it. Rape it. It's yours." A wise ruler -- if that's what mankind is supposed to be -- is one who knows how to work with the ruled, rather than one who simply exploits them.