I have to disagree with that, unless it is on a published (and therefore government approved) no-carry-on (or no-fly at all) list they have NO LEGAL RIGHT to take it. According to the TSA Official Blog E-cigarettes are approved for carry-on, but the liquids must conform to the 3-1-1 rule.
I just flew to and from the states (international and domestic flights) and was asked once what this is (ego battery) I explained, they checked the list, handed it back. Flight leaving the states (actually the domestic leg to my connection) they pulled out my ProVari and swabbed it, then put it back. I of course took everything apart (2 eGos and a ProVari, all with MAP tanks) and put the tanks in the liquids bag.
The only way you are going to have problems is if YOU are being confrontational or acting suspicious. Both times I was asked if they could open my bag and if there were any sharp objects inside. I was polite, answered any questions they had (they actually didn't ask what the ProVari was) and that was the end of it.
When I was a smoker I had my zippo taken on a domestic connection, after flying international with it. I stated that I had just left the international flight, where it was ok, and asked why they were taking it now. They showed me the list, which stated they couldn't be on US flights, and explained it was due to the explosive liquids that could be used instead of lighter fluid. They showed me, in official documentation, where it was not allowed, I accepted that. I did ask if I could keep the shell, which they were more than happy to let me do.
Point is, be polite, but know your rights.
TSA Blog on E-cigs:
http://blog.tsa.gov/2010/05/e-cigarettes-go-or-no-go.html