To run the post-build deliver that is defined in the build definition, you will need to add a separate step to your job to do run the post-deliver (Improve our Team Concert Plugin for Jenkins to support post-build deliver (277270) comment 17 describes how). Not sure if you are doing this or not.

However, the post build deliver does have a restriction. All the components must be delivered to the target to change the ownership (publish) the snapshot to the target (it says this on the post-deliver configuration tab). If you want the owner of the snapshot to be the stream that you just accepted changes from, I totally agree you don't want to be doing the deliver of all the components.

Instead of using the post deliver, I suggest you use the command line (CLI) to change the ownership of the snapshot to the stream/workspace. Depending on the release you are using, the command would be

scm set attributes -s/--snapshot <arg> [--snapshot-workspace <arg>] ([--name
                   <arg>] [--description <arg>] [--ownedby <arg>])
                   [-r/--repository-uri <arg>] [-u/--username <arg>
                   -P/--password <arg> | --certificate <arg> -P/--password
                   <arg> | --smartCard -u/--username <arg>]

or (deprecated in latest release)
scm snapshot promote [options] <workspace> <snapshots...>