An INTP could choose to obey the current authority if she thought it was sensible to do so, but in situations where it does not seem sensible but pointless (i.e., serves no good purpose in the circumstance at hand), the rule gets jettisoned.
"What's the rule for, and does it make sense?"
That is what gets asked.
As far as amoral and immoral, I view the first as indifference to the rules and the latter as breaking the rules. INTPs seem to be more amoral to me.