What a dumb move, timing this with trying to convince people to buy the new warbond. Hopefully Sony reverses this decision after seeing how badly this damages the health of the game.
Unfortunately for those requesting refunds, unless you're in an area that's soon to be excluded, you likely won't get your money back. The game has had the requirement for the PSN account linking listed on the Steam page since day 1, so it's unlikely that Valve will do much in this situation.
Arrowhead isn't free of guilt in this, but Sony and Valve should have both done a much better job at making this clear to players earlier on, since they're in charge of marketing/sales on PC. Like, in-game messaging would have been good for this. They also should have never allowed the sale of the game on regions PSN isn't available to in the first place, since they already knew they would killswitch non-linked accounts eventually.