I'm having a real hard time connecting the dots between your logic, here. If the hardline BoS is 'right' and they should only collect and hoard tech and never help outsiders/wastelanders... then by your logic, they should have not gotten involved in helping in any way in DC, which would have kept the status quo there. In other words, instead of goodness and compassion winning out, fascism being defeated, and humanity in the area thriving with clean water and food and hope for a better world future, the BoS would have just continued to selfishly pick thru the ruins for more tech to sit on for themselves, while the mutants and Enclave mercs preyed on and finished off what little was left of the local wastelanders. Oh yeah, big 'win', that. Not. If 'ensuring their power' at the expense of all of the rest of humanity is their sole goal, then they are truly no better than the Enclave, and are no friend of humanity and deserve to be destroyed.
Acquisition of technology and eliminating the Super Mutant threat as the Western BOS elders wanted Lyons to do would've indirectly helped D.C. inhabitant's a lot more than Lyons' shortsighted decision to protect them at the expense of his other objectives. Twenty years of protecting humanity has brought Lyon no closer to locating the source of the super mutants, has managed to barely preserve the status quo of D.C. as a mutant-ridden hellhole (as opposed to a mutant overrun hellhole), has ensured the steady decline of the Brotherhood in the region, and handed the Enclave the means to exterminate the whole of D.C.'s population on a silver platter. Meanwhile twenty years of zealous focus on technology enables the Brotherhood to activate an immensely powerful asset that is the key to their survival and potentially the security of the whole region.
Again, all evidence in the game indicates that the Western Brotherhood was absolutely right about where Lyons' priorities should've been. At no point did the Western elders categorically object to helping the inhabitants of D.C. they simply objected to this being done at the expense of his primary mission, pursuit of which is what ended up saving the D.C. Brotherhood's asses.
Their original intent was supposed to be to help *all* of humanity, despite their stupidly flawed and misguided methods of attempting to achieve that goal. Lyon's succeeded only because he rejected the fossilized BoS party line, *using* their tech for the cause of good- and that's why the good guys won the day in DC. Sitting on their technology and 'not getting involved' in the plight of the DC wastelanders, would have just ensured the extermination and enslavement of those people. Lyons wisely decided to part ways with official policy, in order to preserve his humanity, and save those under his protection. And unlike the constipated elders of the rest of the BoS, his group actually has a thriving future ahead of it, growing and prospering and evolving. Something none of the other inbred BoS clans are at all capable of. Now that, is 'win'.
But Lyons didn't succeed because he helped people. That had no impact whatsoever on the outcome of the fight against the Enclave. In fact Lyons' helping people almost guarantees an absolute Enclave victory in the region which would've otherwise been impossible. He succeeded because he got a piece of tech up and running the exact same piece of tech the Western Brotherhood felt was more important than protecting wastelanders. They were right just as when they were right to tell him to focus on locating the source of the Super Mutants instead of getting his men killed on pointless search and destroy sweeps to "protect" ridiculous assets like GNR.