Lets try and look at this in a reasoned manner. Jarmel is looking to diffuse the weight of this polls conclusions by throwing attacking the methodology involved in gathering the information rather than the answers that the poll found.
Firstly, Jarmel would have us believe that the people who browse ANN and vote on such polls are not typical fans or typical. By this I presume Jarmel is implying that those people who visit ANN are far more hardcore than your average fan and only really hardcore fans will know who Satoshi Kon is (although Jarmel never explicitly states this I assume it to be his argument. You could read Jarmel's statement as suggesting that those who read ANN are atypical because they are less hardcore).
As far as I can see ANN is one of the most mainstream anime websites around. The anime community, like many modern fanbases, is splintered into thousands of tiny fragments that reside at various locations throughout the internet but ANN has to be the most well known source for anime news and information, well either them or 4chan. ANN claims to be "the #1 English language source for anime and manga news on the Internet." Here is their Alexa rankings, for your information:
http://www.alexa.com/siteinfo/AnimeNewsNetwork.com
How much traffic they actually get is debateable but it doesn't really seem like they much competition when it comes to other websites that offer the range of information that they offer. They're basically like a Kotaku or IGN except they have zero rivals.
Sure, I think we can concede that the most casual anime fans probably don't either visit ANN, or read any major website or contribute anything to any kind of discussion. However, as they're going to remain silent on all matters there really doesn't seem to be much point in considering their knowledge of anime directors because we'll never be able to know what, exactly, they know.
So, while ANN may not be able to speak for every single anime fan on the planet I think their reach is broad enough to give us a broad idea of what your average fan might know about a given subject.
But don't take my word for it, here's another source that ranks people in the anime industry, MyAnimeList
http://myanimelist.net/favorites.php?type=people&limit=20
As you can see, Satoshi Kon is also the third favourite director when using this site, with 2359 favourites.
I thought there were only a couple of problems with the poll? Anyway, because only 8.8% of the respondents in the ANN poll chose Kon as their favourite director you're saying that it's a "bad indicator". However, it's percentage of respondents who chose Kon is kind of irrelevant to the argument at hand. Even though he only achieved 8.8% he was still the third favourite director in the poll and that can't be escaped from by saying "less than 10%" etc.
