This group almost certainly was producing all the metrics that Musk didn't like to look at.

The morale-meter at the company must be negative at this point.

That would be my gut - he felt like they weren't getting the data they needed. If he's doing layoffs/firing that quickly, he's most certainly doing it to make a point to the rest of the company. That's the only reason you would do something like that that fast. Not endorsing it or weighing either way. Just stating the facts.