But objectively, they were intending the physical destruction of whole civilian populations as a means to an end. Objectively, it's like mass abortion to save the planet--- if that's what you think you're doing.
Well at least you're honest.
And by extension that same logic, during the post-WWII Cold War, our side's designation of Soviet nuclear missile launch pads near or upwind of populated cities was immoral ('murder of civilians, objectively') -- therefore we should have simply declared unilaterally that enemy launch fortifications placed near cities would be off limits as targets. The Soviets would decline to enact their own target self-limiting schemes, and would be amazed by our weakness.
Of course our own policy would give the enemy a first-strike capability, and second-strike survivability and capability. Any nuclear exchange would kill millions of our civilians, but few of theirs, because our policy would ensure that their nuclear missiles were safe as long as the launch pads were positioned near their cities -- therefore ensuring that most of their launch silos would be purposely positioned near or in their cities. In a nuclear exchange their silos would not be targeted, guaranteeing their first-strike capability and a reliable retaliatory strike capability if they were struck first.
If the balloon went up, we would all be dead, but at least we would have occupied the moral high ground....
So much for M.A.D., the policy that kept the peace for over 40 years, until the fall of the Soviet Union.
Our WWII bomber crews targeting Dresden were not murderers, and neither were the men that dropped Fat Man and Little Boy over Japan, let alone our post-WWII Cold Warriors that kept the peace in excess of 40 years.