Well shit. The chances of them opening up the site with such allegations being investigated are really slim.
Why is the server actually down is the question. If the authorities have somehow taken it down then it won't be back up but that's bullshit. That's like seizing the entire stockmarket because some of the traders were using funds obtained from crime. But worse still, I think it's a safe bet that every single exchange that exists has been used by criminals to launder coins they stole or got from darknet markets. So can the government just go seize any exchange they want whenever they want?
You're right. Think about all the illegally obtained money which goes into the NYSE and Nasdaq exchanges, the true number is probably in the trillions. Not to mention all the money the PPT pours into the stock exchanges to keep them propped up.