Valve absolutely limits the sale of people’s games.

Usually, this would come in the case of “Hey, this game doesn’t work, we’re taking it out of sale everywhere.” But with Helldivers 2 being so popular and high profile, that wouldn’t have been a good look for Valve. Instead, they limited the zone of sale to prevent customer support complaints.

Sony was limiting where you could legally sign up for PSN and thus play the game, not where you could buy it off Steam. That was a conflict of their own mismanagement and inexperience selling on PCs. Had they been smarter, they would have restricted regions to begin with and there might have been less outcry, but poor planning caused Valve’s parental slap.