When was the last time you saw a lump of meat arc and spark?
Actually, Google "microwave meat sparking" and you'll find plenty of videos --- but in almost all the cases, the meat is cut in a very specific shape (with sharp edges) that makes it concentrate the RF, and of course being a microwave oven the power density is very high. A human body is, to a rough approximation, a bag of water. It will heat, mostly evenly, when exposed to RF (some parts like the eyes do not have good cooling, hence are more dangerous to irradiate, but this is still a conversation about power levels many orders of magnitude higher than a phone would produce.)
Your link takes an award for missing the point. There is a resonant frequency of liquid water in the microwave range which is why tabletop microwaves use that range. They don’t emit a single frequency, no, but I don’t know anyone who claims they do...
Different fields define the EM energy spectrum differently based on use. You can either argue that "microwave" is one end of the "RF spectrum", or that "microwave" and "radio" are two separate sub-categories of EM energy. My field teaches to the latter.
In the end it is an uninteresting point however because it is an argument over what word to use, not fundamental differences in nature. The point I was making earlier which was misinterpreted was that microwave interacts with matter in a fundamentally different way than lower frequency RF, which is critically important to the topic of TFA. Microwaves excite dipoles on the atomic and bio-molecular scale. Lower frequency RF requires some sort of conductive material (or A LOT of energy) to form an antenna, on the other hand, which is why we are transparent to "RF" but not "microwave" (and hence, why some fields treat them separately).
What is your field? What textbook says that "microwave" and "radio" are different? I've been citing a lot of sources here. Just this one from you would be appreciated.
Actually, Google "microwave meat sparking" and you'll find plenty of videos --- but in almost all the cases, the meat is cut in a very specific shape (with sharp edges) that makes it concentrate the RF, and of course being a microwave oven the power density is very high. A human body is, to a rough approximation, a bag of water. It will heat, mostly evenly, when exposed to RF (some parts like the eyes do not have good cooling, hence are more dangerous to irradiate, but this is still a conversation about power levels many orders of magnitude higher than a phone would produce.)