It wouldn't suprise me at all if the AI could see the contents in the cargo of our planets. I would think it's an unintentional thing, could be called a bug. But it might be a bug that we don't want fixed.
Consider some of the other bugs that have been fixed in the past. Populations used to get unhappy at the presence of cloaked enemy ships. And you used to be able to see the contents of an enemy planet yourself by pulling up their planets in the combat simulator. It's very possible that these were fixed only from the players perspective and not from that of the AI.
Geoschmo