Should we all stop eating bananas?

There is no good reason to stop eating bananas. The banana is used as a generally recognized safe food source with an established radiation exposure measurement that is extremely low and considered safe as people have been consuming them for centuries with no known toxic effect.
In fact, using the same Recognized Safe Food Items Scale one banana is nearly equal to 6 ounces of Noritaki mushrooms (Pre Fukushima) 14 ounces whale blubber (Atlantic, or Pacific blubber Pre Fukushima) and is considerably safer than consuming 24 ounces of prunes. Interestingly, frogs legs are very high on the scale and consumption of more than 4 frogs legs per day is considered unsafe. In fact they are considered to be equal to 1/3rd of the exposure of a single chest X-ray.
The Recognized Safe Food Items Scale was created decades ago as a reference that would allow people to understand, in simple terms, the exposure levels of radiation that occur naturally and how it relates to we humans.
Note that the Recognized Safe Food Items Scale lists a large number of foods not generally recognized by Western peoples but are consumed by other peoples worldwide.