I'm sorry but it's clearly a ponzi. It has all the little checkmarks that a ponzi has.
The reasons they gave for their shutdown make absolutely no sense for a legitimate business, but make perfect sense for a ponzi.
Bad press? Irrelevant, they'd still have their trading bot.
C&D? No worries, just move the operation to another country.
DDOS? Either they are grossly incompetent and shouldn't be a 2.5b company or more likely, it's a bullshit reason.

These are on the other hand very good reasons for a ponzi scheme to shut down.
They're basically admitting it if you read between the lines a little.