Claiming that environmentalists aren't phrasing things correctly for the right to care about the environment is pretty much the definition of tone policing. Republicans could easily take up the fight against climate change on their own terms, but the very very few Republicans that have tried have been shunned by the rest of the party.
Rather, let's blame the true villain here, the political ideology that places itself as more important than truth or science, the political ideology that says "if I'm wrong and you can't convince me with science then it's your fault for not trying hard enough." What sort of epistemically closure is acceptable?
People are motivated by different things. Telling them the things that motivate you, and then calling them names when they aren't motivated by the same line of thought, is a very unproductive way to win them over.
You can tell people the "what" till your face turns blue, but if you are unable to hook into a "why" that resonates with them, they will do precisely nothing.
My point is that if you truly believe that this is a matter of life and death, you need to be out in the world pounding the pavement just the same as all the street preachers that themselves truly believe what they have to say is a matter of life and death.
In a similar vein, if the arguments most street preachers give falls completely flat for you, consider the reverse and why what you are saying is falling flat to the people you are evangelizing to. To be effective, preaching has to be for the audience, and not for the preacher. And that is exactly what this sort of advocacy is, preaching.
And even when the motivation is not so sinister as that, people who care about the topic have a particular world view, and they don't spend the time to figure out how their world-view differs from those who aren't as concerned. What motivates one group is not one motivates another. If climate activists are serious about fixing the problem, then they need to abandon the branding aspect and find language that appeals to those not in their target market. Otherwise it's all just a lot of value-signalling.