The money laundering argument is valid. You can´t just say that the percentage of illicit transactions is so miniscule that you don´t need any measures against it. Why have security checks at airports? What´s the percentage of terrorists or drug traffickers measured against legitimate travellers?
What I find annoying is that the red flag isn´t triggered instantly. Why does the software allow you to play and then trigger an email hours later?? If they had a screen come up and explain to the gambler what´s going on and what he has done wrong would be more professional.