Well, if the nuclear power plant is shutdown, then the law would already be L+ meaning nuclear power is outlawed, so why not make it a "coal powerplant" and the big button shuts down the plant, blacks out the state, all in protest of how much it pollutes?
My problem with that is what if Pollution laws are L+? I doubt you're going to find many Liberals claiming that "Clean" Coal Power Plants are "Pollution-Free" (tm), and thus would survive in such an Elite Liberal Utopia. If the Coal Power Plant morphs into a Solar Power Plant if Nuclear Power and Pollution laws are L+, then what would be the motive for the LCS to press the Red Button?
For simplicity's sake, I'd prefer implementing a meltdown that just permanently irradiated the site and killed your squad, leaving the rest of the game relatively unaffected. Perhaps you could still visit the site, but you'd take passive damage each turn and the only thing you could find would be hostile genetic monsters, the occasional friendly mutant, and some weird chemicals (which are a loot type already in the game). Locating the control room again would let you see the charred and looted bodies of your comrade martyrs.
I actually think that meltdown should actually be the intended action, not a horrible backfire. Causing a nuclear holocasut (as a form of political activism against the Arch-Conservative "deep state", of course) would pretty much convince people to abandon Nuclear Power.
EDIT: I just realized something. I need to modify LCS so that, when Animal Rights are L+, the "Cosmetics Labs" become "Underground Animal Testing Facilities", and freeing bunnies are no longer classifed as a crime (being considered vigliante actions).