I just tested this and it is working, but just perhaps not in the way you expect it to.
The primary job of the Jenkins job is to create and/or use a deployment plan and create/initiate a deployment. So I believe that is what the timeout is concerned with. To test the timeout value I configured a Jenkins job to create a deployment plan that has a pre-plan step that lasts longer than the timeout, the Jenkins job stops once it hits the timeout.
So once the Jenkins job finishes its tasks and initiates the deployment, at that point it is done and it has no control over the RA deployment so it just continues to monitor the deployment until it sees a success or failure from RA.