Look at it this way. What's a bigger deal? A fox in the henhouse or a fox on the other side of the pasture in the sights of your rifle?
Hypothetically, a nuke platform in orbit could just lay waste to a massive amount of communication infrastructure. For Russia, operating in Europe, they can rely on encrypted radio comms from London to the Kremlin but the US is on the other side of the planet. US superiority is heavily reliant on things like satellite intelligence, remote guided ordinance, and a central command well back from the theatre of operations.
It would give Russia's outdated crap military a huge leg up and level the playing field somewhat.
I'm not an expert so all that is just me freestyling but how does it sound? Does it sound like a threat to US military effectiveness in Europe?
Russia still has to contend with European armies but they have nukes that they could use tactically in the region. If it's your home turf, you'll surrender before risking that.