Why would you need conditionals for a dialog option? Especially if it's the escape pod dialog. Just have the branch appear after you say you want to go to Taris. Then move the warp script(should be on the final node in the dialog) To after the items. Don't give a option to return to the endar spire so they can't reselect the item node.
If you still need a dialog script I can't help you there. That isn't one of the ones I have.