This is not a security violation. It's his personal info in his personal email account. Granted it has info on people he's offering up to interview for his clearance, but they gave it to him willingly. Little different than an app asking for access to your contacts on your phone.
Stupid to have it just sitting there, but as a fellow cleared person, it is sometimes handy to have reference to that data. A thumb drive would be a better choice, but then I suppose that would be against policy too; bringing in personal thumb drives...
His interview on The Last Word with Lawrence O'Donnell on MSNBC was pretty disastrous.
In what was basically a completely friendly environment he was eviscerated as to his 'plan'. He said he was a single issue candidate, to which Lawrence got him to change to at least a dual issue, of both finance AND gerrymandering. Certainly not bad things, but when you come in as a 'single issue' candidate it's best not to start creeping within 2 minutes of questioning.
All that aside, his point that the other Dems' proposals are basically just fantasy until you fix the two issues he's pushing is still entirely correct.