I have a theory. I think it's fairly clear why this is happening and it adds some clarity to the placement of this Bastion mechanic in the DMG, as well as to the wording of "off limits to the DM" in the video
We have heard in many instances on investor calls by higher ups at Hasbro about under monetization. And we have heard many times about how DMs buy a disproportionate percentage of products compare to players.
An easy, and obvious, solution to this is to give the players reasons to buy those products. Player focused optional rules in the DMG that are "off limits to DMs" as an example. Mechanical changes that make DMing slightly less pleasant but empower players. In essence a very player-centric "update."
So I think that all of this makes sense if WotC's intent is to drive player engagement and spending. It is assumed DMs will just go along with it and continue as is. If players, in a ill-advised desire to take back some power, demand the use of the Bastions, you may even gain a 2024 adoption from a DM that may have sat it out otherwise.
So in my head, it's not hostility to DMs, at least not on purpose. It's courting of players because WotC sees players as an untapped revenue stream. DM opinion doesn't matter, because it doesn't matter if the content is used, only that it's bought.