Then you aren't reading it properly.
Milne & co. ignored the policy set at the conference and also what was agreed at cabinet meetings. They did their own thing, without any mandate but assumed an authority they didn't have and were able to do so because Corbyn wasn't man enough or leader enough to stop them.
Some might think this is the same as what members of the PLP did to Corbyn between 2015-17, but there are two differences. Those MP's were elected and that gives them some legitimacy to exercise their judgement. The second difference is that the MP's judged Corbyn, having known him for years, was not leadership material. Which they were proved right about.
Milne and co were going against policy which is an agreed position representing the wishes of not just the leadership but the constituencies and members of the party. Outrageous. Stop defending them because you had misplaced high hopes. All the things you wanted to believe of Corbyn, that you invested in him, just weren't based on the reality of the guy. The PLP judged him right, but acted wrong. The left judged him wrong and are acting wrong.
And I was just as guilty of the misplaced high hopes and I still like the bloke as an MP.