https://www.lesswrong.com/posts/QDczBduZorG4dxZiW/sam-altman...
In any case, I don't think not responding is an admission of guilt. Assume he was totally innocent. What good does him responding to it do? Would make hundreds of thousands of people aware of it, instead of just maybe a few dozen thousand. An accusation like that is hard to shake off even if you're totally innocent.
That said, I hope if it is true, there's some sense of justice.
I also believe he is innocent until proven guilty, and I completely agree with your last sentence.
I brought it up because I believe it is by far the most comprehensive explanation of this otherwise very odd situation.