If they Fed's have it, that could be a different story, but if that's the case, why did someone take the time to replace the cloudflare page with an official looking "Down for maintenance" page? If they FBI took it down, they usually like to brag about it.
FBI haven't found the servers probably, yet. They only got one admin. They'll make him squeal. That's very easy. 2 choices.
1-Alex tells them everything, he stays in jail for the rest of his life.
2-Alex tells them nothing, he still goes to jail but he'll get some extra there;)
It's only a matter of time now.
I should disagree with you regarding this matter
First of all, he is not in the hands of the FBI yet, he was just detained by the Greek police, though it seems like he was arrested specifically by the request from the US authorities. Further, this dude might be a Russian citizen so the US authorities could encounter some issues extraditing him to the US where he is to be tried. In fact, Greece may have to make a tough choice right now since Greek authorities seem to be slightly pro-Russian these days but the country is still a NATO member anyway. Things are likely to get quite complicated here