What are the rules for who wins when the gold is reached in Saboteur 2?
I agree the the rules are poorly phrased in the "A team wins if:" section.  It provides an outcome tree, but clearly fails to provide a branch for what happens if a dwarf from the other team creates a connection to the treasure, and the way is not blocked for that team by a door of the wrong colour.

Later in the rules, under "Splitting The Treasure" it states:


  Depending on whether there is an uninterrupted path from the start to
  the treasure or not, the Gold-Diggers or the Saboteurs win the round.
  If the path to the treasure is blocked by a door, only the dwarves
  from the team of the same color win.


I think from that paragraph it becomes pretty clear that an uninterrupted path unblocked by any door would be a victory for all Gold-Diggers.  I think your initial instincts were right and you shouldn't worry too much about the sloppily-phrased earlier paragraph.  These things do happen, much to the distress of OCD rules lawyers like us!