That's only a part of it. The FBI as an institution pushes for and against legislation, and when they push they can shove. They play a meaningful role in the actual drafting of the law.
This is not like an inherently evil thing, usually their political agenda, such as it is, it to strengthen laws that make it easier for them to do their work, and push back against laws which restrain their power. They work to protect the interests of their institution, which is understandable, but that necessarily enters into the policy realm.
> You’re meshing the appointed leadership with the field agents, but rank and file FBI and most of their bosses are law enforcement whose assembly line is Justice, not policy, and they’re the guys with the guns, not the creatures with the pencils.
I'm not. When I say "the FBI", I speak of the institution as a whole. Everyone from the rank and file to the bosses.