What is an alternative to "Perpetrator" with a more neutral connotation?

If you mean its leaders, another word that would work here is "instigators," which has a negative connotation that goes with the criticism indicated in your sentence but is not as heavy-handed as, and better fitting than, "perpetrators."

If you don't mean the leaders, "participants" might be a better word than "followers;" as indicated in a comment above, it would seem more natural to say you are a follower of a revolution's principles than to say (about a revolutionary) you are a follower of the revolution itself, as in your sentence.

You can use a straight up synonym for revolutionary such as insurgent:

For contemporary national revolutions, the capture and control of territory has virtually become a "territorial imperative." ... "Mobile war" is required when the insurgent is unable to establish a base in the cities and must continually move to avoid capture by government troops. —The Insurgent State: Territorial Bases of Revolution

Another option would be to use a generic word such as supporter or leader which might have a more relevant nuance.

From a comment under the question, I see that adherents is what was being looked for. However, I think that followers is more natural in this context:

[Merriam-Webster, from the verb follow]
2 a : to engage in as a calling or way of life : PURSUE
       // wheat-growing is generally followed here
2 b : to walk or proceed along
       // follow a path
3 a : to be or act in accordance with
       // follow directions
3 b : to accept as authority : OBEY
       // followed his conscience

Using it in the example sentence:

He criticized the revolution and its followers.

The criticism of a revolution is often of the principles involved and the followers of those principles. These things can exist before, during, and after the revolutionary event itself.

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Google Books Ngram Viewer indicates that and its followers is more common than and its adherents: