Apologies if this has been addressed before. I've searched the forums, the FAQ, and Google, but haven't found an answer to this exact question. To be a little bit clearer, my question is: Does capturing an opponent's Space Dock (using Shock Troops or an Agent) as part of a successful invasion combat count as 'destroying' it for the purposes of scoring objectives (specifically, the 2-point objective for destroying an opponents space dock at the end of invasion combat). To my mind, it could be argued either way. You are removing an opponent's piece from the board, therefore it is 'destroyed'. On the other hand, you're essentially just switching the colour of the space dock, and thematically, you are taking it over, not blowing it up and building your own.

The official rules seem to allude to both interpretations being correct as well. In the rulebook for the base game, under the section where it talk about Leaders, for the Agent, it says: "the active player may replace any enemy PDS and Space Dock on the planet with his own similar units ( normally these units would be destroyed )". That seems to imply the the capturing is a replacement effect, and no destruction occurs. But then, in the FAQ entry for what happens when you capture a Space Dock but have none of your own to place, it says: "No. The units are destroyed, but not replaced ". This seem to indicate that the destruction and replacement are two separate steps. So, first you destroy the enemy Space Dock, then replace it with your own (and if you have none left to place, you skip that second part).

So, what do people think? Is anyone aware of an official ruling on this, and if not, what would you say is the correct interpretation?

This has been discussed before. IIRC, the resolution was that it does not count as destroyed if you replace it with your own. You must choose not to place one of your own SDs for it to count for such objectives.