Agency = the interests of the agent differ from your interests.
Why and how they differ is not that important. What counts is having someone deciding for you, with a different set of incentives.
Activists have two forms of corrupting incentives
Material InterestsFirst are the known ones, which are not much talked about.
Being an activist is a career. Full of incentives. Some of which aren't compatible with being honest.
Say you fight against poverty. You want to say that there is a lot of poverty around. Truth be damned.
Every activists' incentive is to inflate the size of the problem.
Anti vaccine activists will want there to be huge numbers of vaccine side effects.
Climate fighting activists want there to be huge future damage awaiting us if we do not act. It might be true, of course. But note that like any paid operator - the activists will fare better if reality goes a certain way. They have an interest, in other words.
There are careers, salaries, prestige etc. depending on how things are marketed. Some people are honest, but the situation of activism isn't naturally pure. There is a lot to be gained, regardless of what is society's good.
Once you have moral feelings about a subject you lose objectivity.
You might lose your honesty.
A couple of years ago, I walked around with a lady I met.
It was hit by a car while exiting from a U-Turn.
In no way could we know who was to blame. Was the bike exiting irresponsibly into the highway? Was the car driving carelessly?
We absolutely did not know.
Yet, my lady friend told me that she want the car driver to be punished and would testify against her.
This was because of her moral outrage at the situation that got the biking student injured.
Moral outrage is a huge power. It throw our senses out the window.
Moral outrage can be as corrupting and distorting as material corruption.
The intent will not be as corrupt. But the result is the same