I agree with most of that. GM clearly went one direction, but I think missed the mark for the families I know that would be interested. We are a small sample size, and I may be wrong, but at the price (slightly higher than the SUT per like spec, I think they missed the mark) Yes, there is a big Caddy EV in process sometime in the future, and it will have a foldable 3 row. If you look at 2021 Yukon the 3rd row folds flat on top of the interior floor, not below into the frame rails, and the rear cargo floor is higher to clear the rear suspension (so battery length will not matter effect foldability of the 3rd row, what does affect it is wheelbase, the third row has to set in the upright position over the rear axle and then fold down and forward into the 3rd row foot space to stow).With the SUV it appears GM is going after the Bronco and Jeep Wrangler "two row seat" market, instead of the Tahoe or Suburban "three row seat" market. I bet they will produce an electric Suburban at some point, but they have nothing that competes with the Wrangler - until now. So they are entering that market segment with a BEV, instead of an ICE vehicle like Ford is doing. I think it is very smart of them.
I kind of like a lot of information early, as long as they don't follow the Tesla process of promising something that never comes - or comes much later than promised.
The range factor is significant. It would have been wise IMO to squeeze the biggest battery into the SUV, but then it would have to be longer (as you said). And while I agree that a third row is a minimal impact on range from a weight perspective, if you want the third row to fold flat, there might not be room over the battery to make it work. Rivian had to take out some of the battery to get the third row to fold flat. They originally planned to offer the longest range SUV as a two row model only, but I saw a lot of complaints on the forums about that. So now Rivian's longest range SUV will have a smaller battery than the truck, and a third row of seats. People are complaining about that also, but not as much. At least from what I can tell.
So I think GM has the same issue - either reduce the battery to 16 cells (for example) to make room for the third row, or don't put in a third row. Since they appear to be building a Wrangler competitor, the third row is not really needed anyway, so the decision is easy.