I agree with you about personal responsibility. I appreciated this not because I thought it exculpated Ellison, but because I do think that fandom's response to Ellison behaving in truly unacceptable ways has been to treat it, not as unacceptable but as scandalous, which is a very different thing. That has given allowed him to continue and escalate. We've known since the sixties that Harlan Ellison cannot be relied upon to behave like a civilized being on a stage or at a podium. He is responsible for his behavior, and that shapes my opinion of him (which is very low and full of digust). But the people who manage events are responsible for not taking steps to prevent behavior like this continuing under their auspices.
To reframe the problem: There's a guy at my job who continued to try to rub my shoulders or touch my arm after my asking him to stop, and initiating conversations with sexual content. The person I'm angry at is him, and the person I think poorly of is him, and the person I hold responsible is him. But I wrote to my manager and HR generalist, and made sure that they interceded and cautioned him against this behavior, and that was their responsibility because they are accountable for the people they hire.
They took responsibility for the part of it which is, in fact, their responsibility. Con management can do it, too.