It was actually senior Guardian journalists who compromised the cables by publishing the password Assange had entrusted them with. That's what led to the unredacted copies being made available. Jonathan Cook has written about it here: https://www.jonathan-cook.net/blog/2020-09-26/guardian-assan...
> The Guardian book let the cat out of the bag. Once it gave away Assange’s password, the Old Bailey hearings have heard, there was no going back.
> Any security service in the world could now unlock the file containing the cables. And as they homed in on where the file was hidden at the end of the summer, Assange was forced into a desperate damage limitation operation. In September 2011 he published the unredacted cables so that anyone named in them would have advance warning and could go into hiding – before any hostile security services came looking for them.
> Yes, Assange published the cables unredacted but he did so – was forced to do so – by the unforgivable actions of Leigh and the Guardian.