Carlos Danger gave permission to the FBI to seize his laptop and smart phone. So, no 4th Amendment issue if Carlos decides to cooperate. Huma, on the other hand has already testified under oath that she handed over all of her computers to the FBI.

So, a computer was seized for evidence against Weiner in regards to investigation into his pedophilia that extended across state lines. A review of metadata revealed that there were thousands of emails to or from HRC, who had previously deleted thousands of emails from her private Chappaquiddick server (that she was maintaining to avoid FOIA laws); the FBI thereupon obtained a warrant to permit review of the emails to or from HRC. It would seem that the chain of evidence was followed correctly by the FBI and you have absolutely nothing but conjecture to the contrary.

Nothing but praise for Comey when he previously recommends no criminal charges, no grand jury, no subpoenas and immunity to all. Now he's Enemy #1 for doing his job.