Well years ago I saw a design for a cavity filter for 144 MHz designed to reduce the noise in a radioset caused by car ignition systems, it was a dustbin with some added parts inside. The funny thing was that the designer found that if you put a plate of food in the part of the caviety where the electric field is strongest you could cook them with a 144 MHz transmitter. I imagine that with a 100 W transmitter and a bit of time you could heat up a hotdog.
I think that cooking food with a 4W CB is a non starter, but I think that a better way than using the aerial is to put it between two sheets of copper fitted with a coil. Bring it to resonance and then use the dielectric losses in the food to cook it, however unless you want to cook something small like a grape, pea or a gain of rice it will take forever with only 4 W
I very much doubt if a weedy WiFi transmitter in a laptop or desk top router could ever heat up anything.
I would like to know something, the opening poster linked us to an article about the work of the medical doctor. What I would like to know is why anyone would trust a medical doctor on this issue. A knowlege of how to diagnose and treat a disease does not automatically give a person a good understanding into the cause of a disease and vica versa. I think that other professions would be more able to give a reasoned answer to the question of "is WiFi safe from a radiation point of view"