It was probably some noob who sucked at poker, lost a bunch of bitcoin on Seals, and then thought to himself "zomg rigged", and reported the site for breaking US gambling laws or whatever.
It is possible that the Belgian guy is a partially true excuse for why they investigated Seals, to where he was the first to complain, but in reality they finally took action because Caesars bitched or something. I'm just guessing here, but it didn't take 18 months for them to determine that Micon was "chairman" and that he was living in Las Vegas. Obviously something kicked the NGC's asses into high gear in late 2014 or early 2015.
And I'm guessing it was someone/something with influence in the state of Nevada.