> I still haven't seen evidence that they were running understaffed at that moment.
I think the disagreement you see is based on the definition of what "understaffed" means. Having one ATC to do ground and air control simultaneously seems like an under-staffing situation to begin with, regardless of whether it's a common practice.
> Having one ATC to do ground and air control simultaneously seems like an under-staffing situation to begin with
Do we have evidence that one controller did all ground and air? The only evidence I've seen was the NY Times said that, according to a source, two controllers were working and two more were in the building.
In situations like this there is as lot of disinformation. The best thing to do is not add to it - a pile of bad information is not improved by piling more on. The best thing is to patiently find reliable info and stick to it.
There is also the angle of: even if there is an appropriate amount of controllers in the tower at a given time, how they do it can also hint at the issue. Being an ATC is a taxing job, mandatory overtime and 60 hours work weeks screams understaffing to me.