Another issue with the current evil path is that to get on it you actually need to perform an act of altruism first.
Stepping in front of the crossbow to save a mere goblin is not something most evil characters would do. Gale even treats this moment as the very height of heroism when you do it and when he talks to you later about why he trusts you so much. I did it in my game because my Gith reasoned that getting the goblin to lead him back to camp would be the quickest way to Halsin and a cure, but I could see another evil character not consider the option at all.
Is there any way to meet Minthara and join the Absolute without rescuing Sazza first?
Of course. You can either play as a drow (the easiest option) or use the tadpole when you meet the goblins at the camp and they will let you pass, thus won't be hostile. I've never needed Sazza to join Minthara personally.