Darkspilver didn't claim to be a "devout" JW. His declaration states: "My parents raised me as a Jehovah’s Witness, and I have been a member of that community my whole life. Many of my friends and family members today are active Jehovah’s Witnesses. I still consider myself a practicing Jehovah’s Witness, but like people of many faiths, there are aspects of the organization’s teachings and practices that I have issues with."
My English isn't perfect but I think "devout" and "practicing" aren't one and the same. And I see no reasons to question Darkspilver's sincerity and to think he had any hidden agenda. Maybe he didn't "condemn" the org and didn't preach the choir, but he posted valuable information (sometimes overlooked by others) that often made WTS look unfavorably. Also, assuming he had the purpose to "expose & disrupt" dissenters and spent five years doing this - is there a single person harmed by Darkspilver?
Finally, do I correctly understand you - do you think or assume that the purpose of Darkspilver's attempts to quash the subpoena is to chill dissenters?