Have you all seen this:
http://www.coindesk.com/roger-ver-denied-us-visa-attend-miami-bitcoin-conference/Why would the government do this other than to mess with him? Is it because of his connection to Bitcoin or because he renounced his citizenship? If you renounce your citizenship you can't go to the U.S. anymore? I suggest we all mail a cup of fresh urine to the U.S. senate in protest with a label that says, "piss off".
It's because he renounced his citizenship. He has a criminal record, it's next to impossible to get a US travel visa with a criminal record. Also because he was once a US citizenship and has many ties to the US such as family, there is a chance he may decide not to return once his travel visa expires and stay as an illegal immigrant in the US. This is why he's being denied, nothing to do with Bitcoin AFAICT.