While I think I believe this whistleblower, the CIA is _definitely_ willing to troll someone to the point of letting them go testify under oath to the IG. I'm pretty sure they _have_. Not to mention all the LSD they dosed people with.
It also seems like you’d need to troll someone extraordinarily thoroughly for them to have enough material to testify to congress for hours. Even assuming ET is the least likely explanation, it’s at least very curious what else could have resulted in the testimony described in the article.
As the other commenter mentioned - these people troll each other all the time. It's practically the job description for a large portion of them, in fact.
And it doesn't even have to be anybody is trolling him directly. The trolling could be happening several layers deep. And can be entirely unintentional -- just a matter of a few genuinely naive or deluded people somewhere.