Let me add an edit to that quote that I sincerely forgot to add to my original post; I ONLY ever write posts on my personal experience or ideas. Since I do have some experience with these animals I should have mentioned that fact, I'm sorry. I wouldn't refer to them as cardinal rules either, but I did only write that original post with ball pythons in mind.
In the short time I've owned them, I've found MUCH less likely to stress than ball pythons. Exceedingly less likely to stress. My group were quarantined and housed separately for quite some time, the adults were introduced originally for breeding. I haven't seen any breeding behavior but I have yet to separate them from November or so. They seem to be doing fine as a trio. If I were to see signs of stress or resource guarding/domination/competition they'd be separated immediately. But in my experience, with these particular animals, I'm not seeing an issue cohabiting this group.
There are people who have owned them longer and surly have more experience on the matter.
I only give advice on species I've got personal experience owning for what I'd consider a significant length of time. In my experience, this species is more suitable for cohabitation than ball pythons are. But I don't cohabit my ball pythons so other than a basic understanding of the species (which i have) that is my educated opinion. I suppose I should also mention that my specific group of boas are all captive bred and fed on a diet strictly of rodents, they don't and have not ever been fed other reptiles as a food source. Does this change the possibility of cannibalism? No, it doesn't, but I feel it reduces the chance enough for me to feel comfortable keeping the adults as a group.