I hope none of the companies sent this letter respond. As far as I know, they are under no legal obligation to do so.
In fact, if it were my company, I'd refuse to answer their questions but use the opportunity to write them a letter stating *my* views on e-cigarettes, with lots of references to and quotes from studies showing the efficacy of ecigs and the benefits of free-market development, etc. And I would be sure to issue a press release about the original letter and my response.
I see this as an excellent opportunity to publicly embarrass these d-bags and at the same time get the word out to even more people.