I'm pretty sure that the documentary was shot before Heston admitted he had Alzheimer's disease. That's not to say it wouldn't be a factor, but it means Moore isn't "picking" on someone with Alzheimer's. And I've since seen Heston give interview where he was able to make cogent arguments, so I'm willing to wager the disease didn't affect his ability to respond to Moore.
The interview was shot before Heston announced he had Alzheimer's, so Moore wasn't knowingly picking on someone with Alzheimer's, no.
However, its not as though one day you have Alzheimer's then spend the rest of your days drooling in a wheelchair. The disease begins as infrequent and fleeting bouts of confusion, loss of concentration, stammering, memory loss, among other signs, which permeate through normal levels of coherency and clarity. This continues to progress slowly over many months and in most cases a few years until these symptoms have completely encroached upon your entire day. Its not a disease which renders someone a vegetable in a few week's time.
The first signs are typically little more than an annoyance and are often confused for 'normal' forgetfulness, loss of vigilance and concentration with aging so the patient may not seek help for months.
Alzheimers or not... you have to admit some of the stuff Heston has pulled in the past has been incredibly insensitive and in extremely poor taste, completely disregarding grieving families' feelings. I'm not particularly pro-gun control or pro-guns, but holding NRA rallies days (or a week or 2? I can't remember) in towns where there have just been school shootings... that's just incredibly insensitive.
The only fair thing for those who believe the NRA should have canceled their annual meeting to do is break out their wallets and pay for the millions of dollars the NRA would lose in cancellation fees, the millions of dollars planned attendees would lose in cancelled hotel room fees, cancelled airline ticket fees, and compensation for the time off work that was wasted because a handful of stupid people would EXPLOIT a tragedy to stop the NRA from having a convention.
When you cancel airline tickets, train tickets, hotel reservations, banquet center reservations, meeting room reservations, et. al. at the last minute, you lose your deposits or incur a cancellation fee. Thousands of people took vacation or compensation time from work to attend NRA meetings and conventions which were planned more than a year before the shootings happened. Hundreds of vendors invested necessary expenses to reserve vendor space and make travel arrangements.
The least that these idiots could do if they think the NRA should cancel their meetings is to personally compensate every person who would lose money. If they aren't willing to do that, then they should keep their filthy traps shut.
Basically, this is about a very small number of inordinately obnoxious individuals who already oppose the National Rifle Association looking to exploit a tragedy as a platform from which to launch attacks against the NRA.
Would a liquor and beer retailer's association cancel their annual convention due to a string of recent drunk driving deaths? Would an automobile dealer's association cancel an annual event due to a string of recent drunk driving deaths? Would Ford cancel an annual event because some drunk plowed into a crowd of school children with his Ford Explorer? Would an agricultural fertilizer company cancel an event due to the Oklahoma City bombing? Would a fuel oil retailer's association cancel an event due to the Oklahoma City bombing? Would Rider Truck cancel an annual event because of the OK City bombing? Does the ACLU cancel its meetings in California after the rapists and pedophiles they defend in court rape and kill again?
The answer is no on every point. Moreover, would anyone expect them to? Again, the answer is no, nobody would care, because there is absolutely no connection or relationship whatsoever.