Not sure how you think holding up in the Citadel was saving wastelanders. To save wastelanders they just decided to "kill super mutants". That was the efforts of their saving wastelanders, and allowing them to join, BOTH things Maxson BoS does. And Maxson BoS believe they are saving humans from those who would use tech to destroy humanity, so the basic BoS belief is that they ARE saving humans. If you destroy the group who is snatching up people and replacing them with robots, then technically, you saving future generations of people from this fate. IIRC, the BOS in CW didn't want to be in charge of the purifier and IIRC they were transitioning to moving that over to Rivet City control.

Both BoS factions are nearly identical, and for not seizing Tech, Lyons BoS sure took a lot of it. So, yes, they are very much alike, Maxson is just more efficient.

Also, giving a NPCs opinion doesn't make a fact.