The cartoon asks the question "can fire melt steel" and gives a misleading answer.
Yes, fire can melt steel, but only in special conditions as Dr. Thomas Eagar explains:
“The fire is the most misunderstood part of the WTC collapse. Even today, the media report (and many scientists believe) that the steel melted. It is argued that the jet fuel burns very hot, especially with so much fuel present. This is not true.... The temperature of the fire at the WTC was not unusual, and it was most definitely not capable of melting steel. In combustion science, there are three basic types of flames, namely, a jet burner, a premixed flame, and a diffuse flame.... In a diffuse flame, the fuel and the oxidant are not mixed before ignition, but flow together in an uncontrolled manner and combust when the fuel/oxidant ratios reach values within the flammable range. A fireplace is a diffuse flame burning in air, as was the WTC fire. Diffuse flames generate the lowest heat intensities of the three flame types... The maximum flame temperature increase for burning hydrocarbons (jet fuel) in air is, thus, about 1000 °C -- hardly sufficient to melt steel at 1500 °C.” Eagar, T. W. and Musso, C. (2001). “Why Did the World Trade Center Collapse? Science, Engineering, and Speculation”, Journal of the Minerals, Metals and Materials Society, 53/12:8-11 (2001).Ironically, this cartoon found underneath the blogger's tagline, "The miscellaneous ramblings of a surgeon/scientist on medicine, quackery, science, pseudoscience" is actually a double straw-man. First of all the NIST report denies molten steel (likely because acknowledging molten steel would be very problematic for the official story--in contrast to what this cartoon would have us believe). Secondly, molten steel can only occur with the conditions described above by Eagar.
Did the steel melt at the WTC as denied by NIST? According to eyewitness testimony of "pools of molten metal", analysis, and other evidence; yes it did. With very unusual temperatures.
"The temperatures required for the observed spherule-formation and evaporation of materials observed in the WTC dust (table 1) are significantly higher than temperatures reachable by the burning of jet fuel and office materials in the WTC buildings (table 2). The temperatures required to melt iron (1,538 °C) and molybdenum (2,623 °C), and to vaporize lead (1,740 °C) and aluminosilicates (~2,760°C), are completely out of reach of the fires in the WTC buildings (maximum 1,100 °C). We wish to call attention to this discrepancy: the official view implicating fires as the main cause for the ultimate collapses of the WTC Towers and WTC 7 (FEMA , NIST  ) is inadequate to explain this temperature gap and is therefore incomplete at best. The formation of numerous metal-rich spherules is also remarkable, for it implies formation of high-temperature droplets of the molten metals, dispersed in the air where they cool to form spherules." Extremely high temperatures during the World Trade Center destruction, Steven E. Jones, Jeffrey Farrer, Gregory S. Jenkins, Frank Legge, James Gourley, Kevin Ryan, Daniel Farnsworth, and Crockett Grabbe.Is this the only evidence of molten steel? Hardly. In fact, "a fire protection engineer and two science professors" published a brief report about steel taken from Building 7, revealing:
"a phenomenon never before observed in building fires: eutectic reactions, which caused "intergranular melting capable of turning a solid steel girder into Swiss cheese." The New York Times described this as "perhaps the deepest mystery uncovered in the investigation."What does it all mean? The NIST report denies this evidence even though some of it made its way into the previous FEMA report. This is exemplified by John Gross, who denied the existence of molten steel:
There is compelling evidence that the steel melted, and no official explanation has been given. Instead, official reports have been forced to deny the existence of molten steel to support the official story that fires caused the Towers and Building 7 to collapse.
Contrary to the insinuations of this cartoon, the truth is more complicated than the question: "can fire melt steel?" Indeed it can, but not in the conditions we are told existed within the World Trade Center on 9/11. It is an indisputable fact that jet fuel fires cannot reach the temperatures needed to melt steel. Not only this, the buildings were designed to survive plane crashes and jet fuel fires of the kind seen on 9/11.