Thank you for this excellent taxonomy. I think it illustrates a framing issue, I have been trying to address with the whole concept.
As you have described it, all five of our friends have a consistent ideologically sound reason not to die on hill X, and to council others likewise. Even if their ultimate goals are orthogonal, they can all come to an agreement that B proponents shouldn't die on this particular hill.
At the same time, surrendering the hill is a net territorial advantage to Elmer and Don, while the benefit to Alex and Bart is the not dying, and especially not 'dying for no strategic advantage'.
Meanwhile for Carl (and Don and Bart), there's kind of an added benefit to keeping the war cold.(There's probably a better way to describe that, but I'm digressing).
Anyway, my thesis is that there is a unanimous Schelling point here, not to die on this hill, but that only exists if there is unanimous belief that this will be a too the death battle. It is to Elmer's advantage to make sure it is so framed.
Don, Carl, Bart will then respectively carry the water down the line, in order to ensure that Alex doesn't rock the boat. As long as this can be framed as Alex the disruptor, Don, Carl, and Bart will work together to sour the optics of speaking out, which results in Alex's strategic assessment to just surrender the hill.
Meanwhile, Goofus, who is the 0th level true believer of B, will go down swinging and only re-enforce the general stink of supporting X.
I submit that without Elmer's hand on the wheel, Don, Carl, Bart, and maybe Alex(if you allow Goofus as Elmer's foil) would all have seen the disagreement as one that didn't require suicides and casualties. They all would have preferred it be a civil democratic process with respect and room for liberal disagreement.
The Schelling point of ceding this hill, even in the face of majority opposition, only exists because it's been accepted as do-or-die and "don't die" has unanimous support, while allow X has only majority support.
Without Elmer in the picture, the real schelling point might have been X hegemony with allowance for liberal dissent, or eventual hegemonic rejection of X with allowance for liberal dissent.
It is worth noting that not long ago, Goofus held the a similar finger on the scale from the other direction. Back then he was Gallant, but today, Goofus is castrated and powerless and only used as a boogyman of injustice to illustrate the idea that these are "hill dying fights"
Elmer has realized that's how he wins over and over, like a toddler who's parents aren't ready to hand their tantrums. And if anyone has been a parent, you realize that there further you go with capitulating because this isn't worth putting your foot down over, the deeper shit you end up in.