That's a fair point, but I'd say two things in response. First, what you're saying just goes to show that any issues there have been are unlikely to be the result of anti-Assange conspiracies. Second, journalists from a variety of news sources - some of them sympathetic to Assange - have been able to view the hearing. It's not as if some major shenanigans could be pulled without anyone knowing. Nor do I think that the British justice system is so corrupt that it needs to be "monitored", like elections in a banana republic.

By the way, AI's website claims that they will be remotely monitoring the hearings (https://www.amnesty.org/en/latest/news/2020/09/uk-assange-ex...). Are you sure they can't see them?

Edit: I found the following on Twitter. The explanation given makes sense to me. https://twitter.com/StefSimanowitz/status/130328878171446886... (Twitter sucks. Scroll down in that thread to see the screenshot of the explanation.) See also this HN thread: https://news.ycombinator.com/item?id=24491776