Black smoke in photos of the WTC fires showed they were oxygen-starved and could have been controlled.
There is no absolute rule of “black smoke = an oxygen-starved fire”. It’s not as simple as that. You need to consider the materials that are burning, for instance.
Large fires involving plastics produce copious quantities of black smoke..
Experienced fire investigator John J Lentini doesn’t appear to believe you can tell much from smoke colour:
While it is true that flammable liquids produce black smoke, so does any petroleum-based product. The color of the initial flame and smoke might have been important in the 1940s and 1950s when our furniture was made of cotton and wood, but most furniture today is made of nylon, polyester, and polyurethane. Even wood fires, deprived of oxygen, will produce black smoke. According to NFPA 921, Paragraph 3.6:
“Smoke color is not necessarily an indicator of what is burning. While wood smoke from a well ventilated or fuel controlled wood fire is light colored or gray, the same fuel under low-oxygen conditions, or ventilation-controlled conditions in a post-flashover fire can be quite dark or black. Black smoke can also be produced by the burning of other materials including most plastics or ignitable liquids.”
Light smoke may indicate that there are no petroleum products burning. Black smoke
indicates nothing meaningful.
And as you can see from other photos, a simplistic “black smoke = oxygen starved” interpretation is a little simplistic.
Any analysis that attempts to extract meaning from the smoke colour, then, should also consider what might be burning at that point in the WTC fire. What materials were available at that time, and what colour smoke would they be expected to produce? That kind of in-depth review might come up with something useful, but creating fictional rules based on the smoke colour certainly doesn’t.