I'm not going by PnP. In PnP it's generally left to the player to play the patron, so long as the do so in a reasonable fashion. And paladins are the same in 5e PnP. There are no rules for a paladin breaking their oath - it's left to the player to role play.
But in BG3, it's a matter of game balance. If there where two horrible patrons and one nice one, everyone would play the nice one because it makes the game easier.
So, whilst benevolent warlock patrons exist, they will not be available to PCs in Baldur's Gate 3.
I actually suspect one will be more hands off, leaves you to your own devices, one will encourage good behavior, and one will encourage evil. But I also think you are looking at this all wrong...just because one encourages good does not mean all players will just flock to that one...not at all. Good is just a preference for style of play. I actually suspect that once the game is out and people start seeing reviews and such of how fun the evil path will be many will shift to that. Because let's be real here...in most games you are forced to be good and the evil paths are not fleshed out and unsatisfying. Good endings have grown tired, stale, generic, and overall just beaten to death. Press this button to receive praise and better loot, yay, you are a winner. Congratulations on knowing how to follow simple orders. Until the end of the game when it's "press this button to get nothing and die", yay victory!
