That's one of the things I like about this Roleplay - most of the player characters do things that are questionable, demonstrating their flaws and strengths. Even Scalpel's intentions are interesting - questionable acts they are, he's trying to do for what he sees as a good. He sees a future where Machine and Magic will improve ponykind. Granted, for many this is not a good idea, but one can consider it a benevolent goal at the very least. 

Sweeper may have not nuked a town or two, but it's not like she's totally pure. She stole from the bakery, and probably caused a bit of havoc in the past. One time (in her backstory), she lead a bunch of Everfree ponies to ransack a garbage dump, all because the owner didn't listen to the alicorn. And she probably did give some ponies some unwanted haircuts...