I actually just chatted with their support with this question. Their response was that their system is quite sophisticated in looking at all transactions. So, if you are sending/receiving to a known gambling site is a red flag, sending to known addresses on the dark web. I have a feeling that they can tell if hit hits TOR.

I have heard from others on the site that they have been told similar things, like they know that they are gambling so they can only use coinbase as a wallet.. Im not sure if you were to send the coins to another wallet would help. I think if you sent your coins to a blockchainwallet and then waited hours, if not days to transfer the coins to coinbase might help, if one was doing something that they didn't like. but their excuse is that they have to abide by all these laws, so I can understand where they are coming from..

Or go thru a mixing service, but I dont think blockchain.info provides that anymore.. I dont know which ones you can trust..