You kind of miss the point here. The Rushka can’t know which ones work and do not work, so that seriously limits their options.
There’s no way in this situation that they’d risk a limited or tactical nuclear attack, since if even some of those weapons didn’t work that would tell the Americans a lot about the state of their nuclear deterrent and what the real threat Russia poses to the states.
About the only situation where it makes sense to launch with a seriously busted nuclear arsenal is when somebody else launches on you first and you have nothing left to lose.
If the Americans get good confirmation that the Russian arsenal is busted and have pretty precise information about how busted it is, it opens up some interesting opportunities for the Americans. Depending on how screwed the Russians are, it might make sense to push for an ABM shield in the short term that might make their deterrent 100% worthless.