Your entire point seems to boil down to " But i am pissed, i can't just not be pissed, that takes so much effort." , and really that is a horribly poor line of logic, and you then take the step of saying this would cause you fear, not only that, but enough fear that you wouldn't trust this person for the amount of time it takes to walk to your door and close it.
I have to say, that sounds very paranoid, and that is coming from a guy that does walk around armed, on a constant basis. Letting your emotions run your life, let alone feeling justified in this, is how crap like this happens. If the first gent were to simply say to himself "I'll just give the baby his bottle and tell him what i am up to, and if he wants to go further, i'll just outsmart him." he'd be alive today. The knob in question wasn't a sociopath, just a jerk with the same fantasy most jerks have, being dirty harry.
And escalate is a perfectly appropriate word, you know how this person is going to react, and that by giving your answer that you admit is simply emotion fueled, it is going to simply cause him to act more like a knob , than by relating very simple information, that is not going to harm you. He isn't asking for a credit card number, or who you were banging, hell, you don't even have to tell the guy the truth, just make some crap up as to where you went.
Literally the only option that is guaranteed to make the situation more of a confrontation, is the emotion fueled snark of " None of your business." indeed it is none of his business, so lie. If your really that scared of telling someone you went on a snack run , it is the easiest way to not give that ultra valuable information, and not end up in a crappier situation than when you started.