The typical ant is less than 1/10th wavelength at the frequency used in microwaves.(at 2500 mHz w/l = 4.72 inches)
An antenna of 1/10th wavelength will only have a very minute current in it.
To confirn this I just put a piece of sliced turkey sandwich meat, about the size of an ant into my microwave, supported by a plastic container so that it was away from any metal.
After one minute the turkey meat was still as cool as when I took it out of the refrigerator.
You really need to get out more!
You seem to have the answer there.