Muir lost the battle accounting for the founding when the Hetch Hetchy Valley in Yosemite was converted into an early hydroelectricity plant, a role it still plays to this day. There is no one alive today who can understand how beautiful that valley was before it was inundated.
This said, the modern Sierra Club is hardly true to Muir's vision, and has very little ground to stand on in objecting to the industrialization of wilderness.
The modern Sierra Club never sees a wilderness that it believes should be rendered into an industrial park for wind and solar energy.
(A successor to Muir, David Brower, traded the Glen Canyon for the Grand Canyon, as if it was his right to trade important valleys for energy development.)
It seems to me that the successors to Muir are not true to his vision at all. I used to be a member of the Sierra Club, but am no longer.
I note that one of the early chairs of the Atomic Energy Commission, the Nobel Laureate Glenn Seaborg, was a member of the Sierra Club, and saw nuclear energy has a way to protect wilderness from development. He made the point in his writings, the environmental importance of developing nuclear energy. His view was rejected by people who dubiously refer to themselves as "environmentalists."