The problem is that maybe the Soviet Union may not look at it the way your looking at it and figure that if your taking out the Yankees as you find them. The Soviet Union will go with the use it or lose it option with the survivors. They launch we launch and they launch everything else. Upsetting this apple cart is very dangerous. Also the Soviet Union may make it quite clear before the war starts. That if we go after the boomers off our coast they would consider it an escalation and launch a first strike. This is something to consider.
If they didn't put them there they wouldn't be at risk and the Russians would understand they are at risk. The Sov's will be expecting to lose at least some of them as they are quite exposed.