No it isn't. No one is seriously proposing knocking down N affordable units unless they're also including N+X affordable units + M luxury units in the new structure. Any such plan would be a massive waste of time because it has zero chance of being approved.
This article is addressing protesters against "The monster in the mission!!!!1" who marched against replacing an empty warehouse and a Burger King with 16 stories of housing. It is also addressing people like Dwyer who thought they were untouchable and important enough to work against building more housing without suffering any consequences.
I've noticed some attitudes starting to shift out in Sunset as lifetime SF residents find their kids coming home from college or getting married, yet being forced to live hours away. Suddenly the anti-development stance is less attractive when it means never seeing your grandkids.
Ultimately I don't think the Bay Area can muster the political will to solve the housing problem. Too many people benefit from eternally-rising housing costs or have a "screw you, I got mine" attitude. The state government will have to step in and remove local zoning control.