Mostly it is an example of failing at science communication, as highlighting the radioactivity of a banana basically just serves to make bananas seem more scary. Because radioactivity is scary: it can lethally damage without you feeling anything before your start puking.

Saying living next to a reactor is safe because even bananas contains a bit of radioactivity is somewhat like saying living next to a Ebola lab is safe because there are viruses in bananas... it's not really speaking to the fear of getting caught up in the fallout when bad things happen at the reactor.