This is a case of legal if uninformed discrimination. As with any other case of legal discrimination, the best antidote is to publicize the heck out of the case. Everyone who ceases use of their products over this issue should tell them why -- otherwise they'll just assume it's fallout from the economy or something.

Raise this with the NRA-ILA and send copies of your info to news outlets that would actually cover something like this (Fox News, Wall Street Journal, Investor's Business Daily, etc.). If Intuit sees enough business and bad publicity over this, they will find another underwriter (if that's really the issue) or change their policies.