Eh depends what you mean I suppose, but a small dense cluster with enormous outliers is not a great sign usually.

Almost nothing has (effectively) unbounded variance, so most things are under statistical control in a sense. With some notable exceptions (earthquakes, any other event with exponentially decreasing frequency and exponentially increasing damage).

For the sake of argument I assumed the author meant that the variance of the thermostat was too high to be practical.

Statistical control is a very specific term: https://entropicthoughts.com/statistical-process-control-a-p..., and one which you'd expect anyone with a significant interest in Deming to understand.

My expectation is that Lorin would read the parent comment and say some variant of "oh, whoops, I didn't check." As the parent noted, it's not really that important to the overall point.

Short cycling is bad, most residential systems will look like the second chart.

Especially older buildings where things like uneven sun loading have a bigger impact, and where things like outdoor reset are less common.