The certainty bump is a function of a variety of different aspects of the lack of response, including the fact that he didn't even say something like what you suggest about ""Interesting. Why do you believe that? And that he's not responded even as this thread has grown, and he didn't respond to either PMs (apparently) or the first public call out.

There's also an aspect of personalities that is relevant here. Frankly, I'd expect you to say something like your suggested response whether or not you were actually engaging in the behavior in question. If Eugine were not, given the rest of what I've seen of his interaction, I'd expect that he'd be substantially more likely to vocally deny it, since he's generally blunt. And the 10% to to 50% has included finding out related information such as the fact that twice before ialdabaoth made direct comments to Eugine about this that got no response at all. See here and here.

So I should clarify that the movement from 10% to 50% is not just Eugine's lack of denial, but the complete lack of response and finding out that this isn't a new thing at all but something that has happened repeatedly previously.