The people who are saying that excluding books from libraries isn't banning. It's straightforward. Discussing this reminds me of arguing with my narcissist father - he slips through conflict by redefining terms to fit his inability to take accountability and recognize that his actions have consequences.
It really is a bad look to argue like this for a group of people who are trying to accomplish a goal.
It's pretty clear that if the books they are banning from these places were unconditionally banned they wouldn't go to bat for them. Rather the sentiment would be "that's good actually." It doesn't take a genius to recognize that the playbook is to make incremental advances and argue over definitions in order to achieve this goal.
It absolutely is a coherent argument and you know that.
"Unconditional availability" inherently excludes "banning" and also "conditional banning" but the latter is a mere subset of "banning". Denying the distinction of the sub- and its superset is extremely intellectually dishonest when that's what the entire argument hinges on.
When I dump hundreds of tons of a book into a river a day and the government requires me to stop doing that, it's not banning the book from the people living downstreams, even despite the availability of the book being reduced for them.