The question is, can you afford NOT to hit a boomer that is about to launch a nuclear weapon on your territory, even if it's announced to be an uninhabited island. Boomers are strategic weapons. You don't do show of force with them, just like you don't with land based nuclear missiles, or bomber formations. The enemy knows that you have them, that's enough. A boomer has what, 24 nuclear missiles with eight warheads each? Put yourself into the shoes of a Russian officer - the whole thing is about to escalate, but your leadership so far hasn't indicated that it's willing to back down. And here you have the option to a) Strike at the enemy while he's busy making a mistake b) eliminate 192 nuclear warheads in a single blow that are otherwise likely to be launched at your home country a day later (and that's all based on the unproven assumption that the enemy is telling the truth about his intentions)
