> If Ukraine could deploy actual Terminator robots to the front line it would do it in a heartbeat.
Completely false. They are beholden to their allies. Ukraine could also reach Moscow with missiles, why doesn't it? It could build a nuclear bomb in 6 months, if not 6 weeks, they have the capabilities, why doesn't it? It's not so simple.
I think the reason Ukraine has not attacked Moscow with missiles is that this would force Russia to retaliate with nuclear missiles. There's a long discussion on this in sources I follow (full disclosure, I tend to listen to John Mearsheimer a lot although I don't believe everything he says) and the consensus is that the latest attacks in Russian land will have consequences.
So I agree that it's not so simple but I also don't believe for a minute that it has anything to do with ethics. Not in that war. And I have to be honest but I can't think of a war were ethics played an important role in determining belligerent's behaviour.
> Ukraine could also reach Moscow with missiles, why doesn't it?
Ukraine doesn't have enough missiles to reach and hit important targets in Moscow.
Due to Moscow having the best defence, it doesn't make sense to try to hit it only for lulz, instead of hitting actually important target elsewhere, like oil refineries.
Otherwise, Ukraine has constantly been trying to hit targets in Moscow and around it, mostly with long-range drones, not missiles. Sometimes this has been successful. I mean, the dome of the Kremlin itself was hit a few years back.