In the wiki documentation, under "Automatic Rebase" section, it explicitly states ability to rebase to a point created with "Promoted Builds" permalink:
Specifying the build to rebase to is a good way to control the frequency of the rebase. For example, imagine using the build promotion plugin on the trunk, and promote a build as "rebase point" about once a day (contingent on passing QA jobs.)
However version 2.3 of the plugin does not list (nor let use) any Promoted Builds permalinks, it only show default "last, stable, unstable, etc, and Last Integrated"
Please note this problem is only with Build Action that is part of regular build steps. The manual "Rebase from Upstream" link on the left of project does show custom/promoted builds permalinks.
The "Rebase" build step shows the child/branch permalinks/promotions, while the manual action "Rebase from Upstream" and documentation use parent/trunk permalinks/promotions