Actually, F (especially Fe) is rational. Only perceiving functions are irrational.However, I realized in my late teens that it is productive to take what is 'irrational' into account and for this reason I have learned to emulate F behavior to some extent.
Okay, the bold part does hint at you being a thinking type.This doesn't mean that I am a maschinenmensch (my inner core is wildly vulnerable) nor does it mean that my warmth is calculated. I am strongly attached to those who are closest to me, I am sympathetic to those who are peripheral and I am cordial with strangers. All of it is sincere feeling; what I had to teach myself was to be aware of it and to express it.
I think anyone could make an impersonal decision about an impersonal situation. I would be able to fire thousands as well, as long as they were people I didn't care about. As for sleeping at night, I would be able to as long as I had security guards and such. (Those workers might hold grudges, so I'd be sure to be prepared for their assassination attempts. Better yet, I'd try to do it anonymously if possible.) Also, most introverts can appear somewhat cold and formal to others. I'm certainly described as formal and serious more than anything else.Outside of what is personal, though, I am as objectively tough as they come. I could make the decision to lay off thousands of people and still sleep well at night. When I described myself as cold and pompous, I really wasn't kidding.
I don't understand either how conscientiousness is related that much to sensing. I think it's odd.I don't get either why anyone would doubt my iNtuitive preference, but I am waiting for Jen to flesh out her claim that I am primarily detail-focused. So far I suspect it is a case of INTPs and INTJs having totally different priorities and my attempted explication of mine confounding Jen. (There are probably some finicky posts of hers that I could be convinced were evidence of a Sensing preference. )