Given the game recently went free to play and many people still play it, its not surprising blizzard are not releasing the source. If the game had been dead for 5-10 years, then sure, they should probably release the source. Its still going strong and shows no signs of stopping in the next 5-10 years, especially now due to the remaster.
There are plenty of other games out there to learn from using the source, if that's your goal.
> For goodness sake this thing is older than half of people on HN.
Are you saying that half of HN are younger than 19? I would have thought the average age on HN would be somewhere around 30. I would expect the average HN person was a kid or teenager when Starcraft was released.