I can't believe that while you're digging for reasons to support your belief of Economica not being an INTJ, you're missing the major flaw that deteriorates your argument.
Can you seriously not see that, as she mentioned, she had a sort of epiphany re: herself (the CC business) and is digging to find any piece of something that will help her understand herself more clearly? Isn't that what every INTJ does? Have we not discovered that INTJs post wayyy more about themselves than any other type?
I think it has far more to do with us having an inner drive to understand and be understood than it does from anything else. This CC business of Economica's is INTJ driven.
So, believe she's not an INTJ, fine, no problem. But insist that she can't be one because of her online behavior in an environment that is not representative of the real world? That's just immature.