How do I hard/instantly set the joint positions through a ROS2 node?

I’m trying to control a custom robot which has two unactuated joints. Later the robot should be controlled so these joints do not sway as much, but for now I just want them to have the position 0 as soon as the other joints have reached my target. Manually this is easily possible by selecting the joint and putting a Zero in Physics>Joint State>Angular>Position.
After going through the tutorial (7.2.10. ROS2 Joint Control: Extension Python Scripting — Omniverse IsaacSim latest documentation) I tried to publish a JointState with everything being 0 but I guess the publishing of a JointState can’t instantly set a position:

joint_state = JointState()
joint_state.name = [‘universal_joint_trolley’, ‘universal_joint_pulley’]
joint_state.position = array(‘d’, [0.0, 0.0])
joint_state.velocity = array(‘d’, [0.0, 0.0])
self.publisher.publish(joint_state)