I got what you meant all right.
What I meant was that once they say: “fill it up”, they can do a surprise launch.
Suppose they are not going to back down from a launch.
Their liquid fueled rockets have better performance than our solids in that scenario.
This destabilizes the MAD doctrine.
If the missiles are so bad they can only be primed once... That’s still their problem. As their victory will be worse than Pyrrhic.