In the 6+ months they knew about it, not one person realized PSN access wasn't available in all the countries they were selling to?
Localization and regional sales are typically some of the very last tasks in a game's development cycle, and six months is a lot of time for a memo to get misplaced. Configuring the Steam page's region settings for the game very likely happened in the last couple weeks before release, and somebody very likely applied the wrong default settings (likely using settings Sony would normally use for games that don't require PSN).
Not that that makes it okay, but it's not like there was some secret conspiracy at AH/Sony to hide PSN linking and intentionally sell to users they're guaranteed to issue refunds to. This was a combination of bad business decisions, poor communication, and most likely a dash of human error.