Open source researchers on social media suggested a Krasukha electronic warfare radar jammer had been positioned on the complex.

That's why. The jammer is messing with Ukrainian operations and Russia put it there so they could scream "nuclear site!" if Ukraine ever went after it.

I guess they are trying to achieve the possibility of a decisive first strike for USA.

Well that's not at all concerning...

I used to think nobody was stupid enough to kick off an apocalyptic nuclear war but in the last two years I feel like that belief may have been a bit naive.

Well it's Russian infrastructure on Ukrainian land, who cares what it's for?

Because any country fighting a war on defense against aggressors/invaders knows that the path to winning is to hold strong, wait out the clock, and drain resources from the enemy. Something as essential as that will cause urgency to redirect resources and personnel to replace/repair and then better defend it so that it doesn't just immediately happen again. This makes defense easier because there's less of an offense while that's happening. This also can cause internal loss of support since Russian citizens can see the costs of this going up. They will know people who were sent to die on the front lines. They will see taxes go up and availability of goods go down. Once Russian citizens start to question and criticize the campaign, there could be a snowball effect that ends with Putin and his cronies having to make a choice between stopping the invasion or losing power. I don't think Putin will ever stop, so the real choice will be desperate attacks (which could include nukes, triggering article 5 and effectively ending Russia) or a coup. Putin has checkmated himself whether he is aware of it yet or not. His best case scenario at this point is dying of natural causes in office and leaving that hard decision to his successor who will probably back down and be a pariah for it, saving Russia in the process.

Where are you reading that is a radar for ICBMs? The article just says a Krasukha radar jammer is reported to be there. Reading the Wikipedia article for these systems indicate that they can jam the radar for UAVs and drones. Since Ukraine has been using drones heavily, I can see why they would attack. I’m not saying that it doesn’t work against ballistic missiles but it’s seems like they have a lot of other applications to Russia’s war effort.

I would guess this is likely to get Russia to dedicate more forces to protecting their nuclear capabilities because without that Putin knows he's fucked.

The more anti-missile and anti-air are dedicated to protecting nuclear triad infrastructure, the less is protecting other assets like HQs, supply depos, aircraft and other conventional combat systems.