After all, most people would say (I think) that once you've done a particular immoral action once or twice, it becomes easier to do it later. I'm talking here about personal morality rather than any kind of universal morality, of course.
[Bm] "Command", "normative force", and "should" are just different labels for the same thing, whatever that thing is, if it exists. You can't get an ought from an is, so there are no arguments proving that one should do this or that, except from assumptions about what one should or should not do. There isn't an argument proving that you should get out of the way of a car either, only a description of the consequences, on the basis of which everyone is free to make their own response to the situation. "Enlightened prudence" (with an emphasis on the enlightened) doesn't bridge that gap, but neither does anything else. The only way to get there is to be there.
[Bm] I left moral truth off that list, because although one view is that it's just another name for the same thing, in the view I'm arguing, it isn't. It's...it's moral truth, that's what it is! And one still has a choice about whether to follow it or not.