Hi, I'll try to be nice and direct for you =) Ordered as your questions:
That's what I was expecting. I appreciate your answers, thanks!
"Proof" of illegal activity is a matter for legal courts, not for our staff to determine. We of course do not intend to act "on a heuristic basis with frequent false positives." Putting a hold on a suspicious account is not calumny- calumny requires an intent to slander or defame someone with false knowledge. Ironically, if you knew the definition of that term, then you almost committed calumny against us, didn't you! 
Almost.
What I meant is that if you claim that you only freezes an account if it is "to protect the owner" or "when owner acts illegally", and someday you freeze someone's account without being for his own protection, than you're by exclusion saying the owner is behaving illegally. Of course, if you always add the word "suspicious", never making direct accusations etc, I guess you won't have any sort of legal problem. I just hope your heuristics are not like some others we've been seeing around, if you know what I mean.
I wish you success on your business. Best regards.