"Unavoidable"..."Fixed" might be a better descriptor. "Etched in stone." The past cannot be re-written.
However, in the writing of future Episodes, Doc will need to make canonical assumptions based on the literal divergency of canon which is the nature and side-effect of choice based games. Many forks in the road behind us. It's unlikely that he has the time and inkling to write scores of divergent storylines from the get go to spiral off into many new forks. He would need to write literally hundreds of storylines just for a single Episode from 5 Episodes full of choices. Therefore he'll need to make assumptions. Meaning he will have to discard many elements that are not "fixed" or "etched in stone." Ideally Doc could write elements into Episode 6 that involved not fighting Caleb, fighting him and losing, and fighting and winning. But that right there would create dozens of branches and so is impractical. So it's not unreasonable that non-fixed or non-canon elements will be either ignored or discarded...for now anyway.
For example in the (excellent) game City of Broken promises, the MC has to go to a high class party to gather information. You get to choose which of three different female NPC's you want to bring with you. Each girl results in a completely different party scene. Clever. Well, later in the story, Victoria, one of the girls, references something that happened at the party during her scene, even if you didn't choose her in your run-through. It's a blooper...but understandable. Games like this are like trees with potentially thousands of branches and twigs. It would require a large staff to cover every possibility. And DrPC, brilliant as he may be, is just one guy.
We as players will need to "suspend our disbelief" a bit, and be gracious to the writer, understanding that the next episodes may not be impacted by some of the choices we make in 1 to 5 even though we might like it to. For now, as he indicated in a recent Update report, he's doing the best he can. That is until the game become more of a phenomena and Doc hirers a full writing staff. Then....BOOYA BABY!
