While I agree that things could have been consulted beforehand, this whole thing is something that I have displeasure with at scanlation culture, with stories being monopolized and aggressiveness soon arising as soon as any competition arises.
I do prefer the DnA quality and I'm re-reading all chapters with them even if I read them first with the other group due to impatience, while I agree that taking a different project would mean a wider range of scanlations available I don't see what's such a big issue with another team stepping in, the exclusion feels way more toxic by comparison.
Back when I was younger, I remember that in anime, there would be anime translated by like 3 fansubs at once, each with different approaches for different publics and never saw anything troublesome arising, so I guess this is something unique of scanlations?
I simply hope that this issue is resolved in a peaceful way, as make too much drama arise will just sour everyone's mood.