Thats not how it works in the real world. Reputation matters, for good reason.

If 'Animats comments on tcp/ip you should trust it more than if I do.

If 'tptacek comments on app security it's sort of the same (though I don't know he has anything named after him).

Making a claim while not explaining your reasoning is a sign of a low quality post that provides no actual contribution to the thread (and more often than not, of trolling) which justifies downvoting the post, no matter who the creator.

Reputation matters if you want to buy something or if you want an expert opinion on a topic that you have no idea about. However I don't believe that reputation matters in a forum full of people who would be able to understand (and wish for) a reasoning behind a claim.

A warning from a knowledgeable person without explanation is still better than no warning at all. I hope tptacek just didn't have time to post an explanation; maybe he'll find the time later.

I'm on vacation in the middle of Austria with spotty Internet access, so you'll all have to take what you can get. :)