It was never an agreement to get Moxxi "introduced" back into the Sith. It was simply a method of making it easier for Moxxi to obtain Emperor if and when he gets un faction leader banned, and that is where this all stems, the loudest, most toxic members of this community make it known that they want Moxxi as Emperor but the little guy who actually wants to get somewhere doesn't want Moxxi anywhere near Emperor, it's already as bad as it is with him breathing down Macklin's neck and "Advising" him. Like everyone is just beating around the bush here and giving Moxxi these special spots and permissions just so he can get Emperor that much easier.
edit: And it makes it all that much harder to get a reasonable opinion out there where everyone is so dead set on one thing and one thing only. To progress as a faction you're gonna need to have an open mind to new leaders. If you constantly look towards the past on how to improve your future you will never truly make steps forward, you are taking them backward. Cut the shit and stop relying on the past to fix your future mistakes. Take risks when deciding on a new leader. I want to see how Macklin does as Emperor just so he can prove these godforsaken Moxxi cultists wrong. But he has to make Moxxi rise the ranks normally.