I think you're confused. These are not words they chose to study - these are the words with the largest difference in recognition, from a larger corpus of words.
You're projecting some kind of pre-bias onto the researchers that I don't think is there.
Perhaps you're right. I read their methodology and it seems fair. They did solicit demographic info from the participants, but didn't mention if before or after word testing. There's still wiggle room there for bias, but probably not.
I think you're confused. These are not words they chose to study - these are the words with the largest difference in recognition, from a larger corpus of words.
You're projecting some kind of pre-bias onto the researchers that I don't think is there.