I think you're confusing "terminal" and "immutable". Terminal values can and do change.
In my current condition I wouldn't build a baby mulcher
And why is that? Do you, perchance, have some terminal moral value which disapproves?
People terminally value only what they're doing at any given moment because the laws of physics say that they have no choice.
Huh? That makes no sense. How do you define "terminal value"?
As far as I know terminal values are things that are valuable in an of themselves. I don't consider not building baby-mulchers to be valuable in and of itself. There may be some scenario in which building baby-mulchers is more valuable to me than not and in that scenario I would build one. Likewise with doomsday devices. It's difficult to predict what that scenario would look like, but given that other humans have built them I assume that I would too. In those circumstances if I could turn off the parts of my brain that make me squeamish about doing that, ...
Part 1 was previously posted and it seemed that people likd it, so I figured that I should post part 2 - http://waitbutwhy.com/2015/01/artificial-intelligence-revolution-2.html