Just by origin of the word polyglot means you have many tongues. Tongues is of course well established as a stand-in for languages. If you can speak more than one, you fall under the definition.
I think people have attached more to the term than just that though. I'm thinking of well traveled and culturally sensitive as well. Somebody who would be alright no matter where you dropped them.
How many languages can your better half say good morning in? She might just be trying to pay you a compliment and you with your humilis gloriatio are not having it. In any case, I wouldn't recommend going back to her with arguments obtained from a random group of internet users to settle your interpersonal disagreement.
Perp walks. Teachers in school in front of class. Other kids in school being mean. Public dress downs at work. I'm sure there are more. Not all perps walked reoffend. Kids get their shit together because they don't want to be made to look silly in front of their peers. I think for some employees this works similarily.
Shaming only works if the shamed feels any. The doublers-down are often the ones who don't feel shame. So it was the wrong tool for the job. Won't work on 47 if you know what I mean.
Just to clarify: I would personally put this tool in the "break glass in case of last resort" section of the tool box. But I've worked with bosses who didn't put these restrictions on themselves and it can work.
You could question their leadership qualities if you wanted to. That's a benefit of arm chairing this stuff in an internet forum.