Long ago I tried a mod that allowed killing Preston but it had some issues. I just used the default Conqueror start to mow down these parasitic leeches while still in the museum. It felt so good I saved, reloaded, and did it again. No comment how many times I reloaded. If there is every an update to this or a feature option, I'd like the ability to save Sturges. Recruit him into my gang, then butcher the rest. He's the only one I can stand.