She's fun character for sure. As a Lolth Eld Knight, my justification for not attacking her is "Why she turned her back to Lolth?" I am looking at it as. I am doing Lolth's will, what is stripping my Goddess of her Drow. I will find the root cause of it. Kill it and free all her subjects to serve under Lolth once again. So for now, she is only there for me to investigate!
I think this is an option for the "chaotic evil" passage. Help Minthara deal with the Absolute, then betray her for Lolth, who wants to punish her for apostasy.
I like this option, it will appeal to both Lolth fans and Minthara fans. But in this case, I will help Minthara and get more trust and respect from her by protecting her from the clerics of Lolth. Together with Minthara we can be a good team and against everyone, including the cult of the Absolute who deceived her with a tadpole, clerics of Lolth, and good characters who will condemn our methods - that would be a lot of fun.
I think this is how the perfect path of "lawful evil" should be. This is the path that will allow you to combine honor and friendship, evil roleplay and personal gain. I would like this roleplay, and I really hope that Larian will make it possible.