That was a particularly odd choice on his part. He could rather have cancelled all other versions and stuck to this, for the good of the project. Perhaps he doesn't really feel this is his computer anymore, or he doesn't realize that as the father of the project, abandoning your child will look terrible in the eyes of the community. I would call this his biggest blunder to date - at least from my POV.
Not sure how far back you're quoting but the X16 version is very much happening and David can't wait to start.
It's true that it didn't make much sense to start writing the port while we were having problems with the prototype (to be expected with any project) but he's only waiting for feature lock so he doesn't have to write it twice.
The rest of what you say is hearsay and not particularly helpful, nor accurate. We're already discussing his "Part 3" video that he's making.
I realize speculation can occur when we don't design the entire computer in the open, but as I say to others, please remember how unprecedented the level of access we have given is. Have you ever seen this openness before in any major project, before crowdfunding even starts?
To summarize, Pet Robots is happening, David's next video is being planned, and there's nothing more to it really. ¯\_(ツ)_/¯