That's just ridiculous!!
I would think you could carry 500 ml in 50 or 100 ml bottles easily in your checked baggage. You couldn't carry it in your carry-on. I heard though there is a new law coming out that supposedly prohibits transporting e-cigs even in checked baggage. I don't know if there is any truth in that or just a ecf rumor. It doesn't sound like they could get away with that but who knows.