This was a pretty short sighted horrible idea, imo. You are incentivizing people to watch only select list SDS deemed appropriate. Even worse though you're deincentivizing any streamer not on that list to not stream your game over the weekend as people are actively going to avoid their channels.
Plenty of games are able to turn on drops for all streamers, I think this decision was in poor taste by SDS and honestly inhibits the growth of this community/game.
Is it not the Sony partners that are getting the twitch drops? If it is then it makes perfect sense, who else would they give it to?