It's not that the poker sites failed to block countries where online gambling is illegal, it is that they allegedly committed bank fraud (and money laundering) by masking payments from gamblers in the US as non-gambling related items so as to avoid the attention of the banks and authorities.

So for example, instead of a credit card statement showing a $100 payment to PokerStarts.net, it showed a $100 purchase of a teddy bear from a shell company.

They were not passively enabling US based people to break local laws, they were actively assisting.

Fair enough, and they probably deserve to have their US assets frozen. But a .com shouldn't automatically be a US asset simply because the .com root happens to fall in US jurisdiction.